This is a hard choice to make so I'm going to go with what my guts tell me, along with what my mind allows me to remember.
From Best to Worst favorites:
1. RE3 (Was the most intriguing and had better gameplay out of the three in the original trilogy. It also introduces a decision-making system; something that I was extremely wowed about. With this system, your actions can alter cutscenes and dialogue in many ways and most areas have the ability to randomize items and enemies in different playthroughs. Also has the best tyrant and much more better setting than its predecessor. This game has happened to be my most favorite ever since I first played it over a decade ago)
2. RE2 Remake (Best Remake ever made since RE1 Remake. It's a masterpiece of a classic that's not even my #1 favorite and loved almost everything about it. Only thing keeping it lower is the timeline inconsistencies between both Leon and Claire's campaigns with their 2nd playthroughs, only changing most, if not, some of the item/enemy placements and dialogue, with even less plot changes than the original. However, this is just a minor complaint I have as the Remake literally improves everything else about the original game.)
3. RE4 (One of the best games I've ever played and extremely fun with a considerable amount of replay value. Only reason why I would rank this higher than 5 and 6 is due to me having one of the best memories I have with both this game and my family as a whole.)
4. RE6 (Has the best plot and background story, along with its awesome plot-twists. Also filled with immersion, great atmosphere, character development, and best modern gameplay mechanics since both RE4 and RE5. with also considerable amounts of replay value. Because of this, I regard this as one of the most underrated titles in the series.)
5. RE Revelations 2 (Pretty much on par with my likeness on RE6, except that Raid Mode felt lacking as it had unnecessary excessive amounts of repetitive farming and was dissatisfying in terms of difficulty, even on Code Red since once you get OP weapons and skills, nothing can really kill you.)
6. RE5 (Best game for playing against your friends on versus mode as I happen to have so many fun memories about it. Plus, it has a lot of memorable moments for a modern RE game and improved gray areas in which RE4 had, such as better uses for QTEs and better gameplay mechanics.)
7. RE1 Remake (Best Remake for its time and was one of the best looking GameCube games, thanks to the advantage of better pre-rendered backgrounds since the original trilogy. It is probably my second most favorite classic RE game but as with all the other classics, it hasn't aged well with its gameplay, mainly with the FCAs.)
8. RE Director's Cut [DualShock ver.] (Been one of my favorites as it was the first game I ever played in the whole RE franchise. A lot of great memories too and has mostly better music than the original imo.)
9. RE0 (A great prequel to RE1 Remake. Has one of the best duo gameplay mechanics that I've ever seen for a single player game, hence the return of these mechanics in Rev2, which fit in really well. However, the inventory management and severe backtracking holds this game back from being close to being my near favorite with RE1 Remake, but is bearable after a long while.)
10. RE2 (My least favorite in the original trilogy but makes up for being the first RE game to have proper character development, especially with the mother/daughter relationship between Claire and Sherry, which felt more real than Leon and Ada's forced and dramatic relationship, which should've been more like a Jill/Carlos relationship than a romantic one. I was never too fond with the A and B scenarios since it forces you to play the game two to four times in order to get the whole picture of the entire plot and is more or less the same, save for a few plot and item placement changes. Nonetheless, it's still one of my favorite classic games to play from time to time.)
11. RECVX (Initially the hardest RE game I ever played until I came to play Outbreak, but makes up for a real challenge and overall, having one of the best villains that I came to love for the series; Alfred Ashford. His insanity and background story just makes up for a perfect villain of the series although at the end, came up to be part of a wasted potential for the series as a whole. Alexia wasn't at all intimidating as Alfred, but she shares some of the insanity that her brother has and the game's settings, both the Island and the Antarctic, really reflects both on their dark personalities by milestones.)
12. RE Revelations 1 (One of the best 3DS games I've ever played and probably the best looking 3DS game there is. This game has a good plot, but leaves too many plotholes with its ending, putting up more questions than answers. Another thing is that the game had potential for having a pretty decent amount of character development, but didn't put much emphasis between the relationship of Jill and Chris as it simply felt more focused on Parker and Jessica with Quint and Keith being slightly out of place for the series, but fun to look at their characteristics. Gameplay is smooth and its Raid mode is better at giving a rewarding feeling after playing a stage, even at the highest difficulty with the most OP weapons you can get.)
13. RE Outbreak [Files 1 & 2] (The hardest RE games there is in existence for me. Even normal mode feels like it's more of a hard mode and the virus meter never gives you time to explore your surroundings. Inventory management is on par with RE0's, and the AIs are even worse than the RE5 AI. Never fully completed File 2 but I still enjoy both games nonetheless.)
14. RE Operation Raccoon City (Story isn't perfect or even the worst but it does have a decent one on its own for a what-if RE game. The main reason why it would be up here is due to the fact on how much fun the game is to play, especially with friends. I actually had a lot of fun playing mostly Heroes mode as Claire, Jill, and either Ada or Nikolai. The CQC killing animations were the best part! Never regretted playing this game, not one bit.)
15. RE Umbrella Chronicles (The Chronicles games have their ups and downs altogether but gameplay for this game is more stable than the waggy camera gameplay that DarkSide Chronicles have. The retelling of RE3 felt like it was rushed and having to face Nemesis at the final scenario for the first time was kinda disappointing, especially his robotic voice. Everything else was pretty much fine and the whole game is pretty fun to play and well made as an on-the-rails shooter type. My favorite side-scenarios are the Nightmare ones with Rebecca and Richard.)
16. RE Darkside Chronicles (Same thing with Umbrella Chronicles, except this goes below UC due to its horrible camera wag being a nuisance for the most part. The retelling of both RE2 and CVX were pretty amazing and so as Operation Javier, which makes up for being pretty much on the same level as UC.)
17. RE Mercenaries 3D (Real fun game to play on 3DS, with or without friends. Has quite a collection of awesome soundtracks of its own and even reuses both RE4 and RE5s soundtracks from their Mercenaries and versus mode. Stages aren't as big as their originals but have a wide variety of enemies for you to fight against, along with swapping out your customizations and such.)
18. RE Gaiden (A nice RE game for a GBC game. Even its mechanics fit perfectly well that it makes you believe it's an actual RE game, except for its combat system. I wish there could've been another way of dealing with enemies using a different combat mechanic but other than that, it did well for surprising plot-twists that came almost as a basis to what RE6 would later use for its plot, which I really loved about. Definitely an underrated classic because of this.)
19. RE Dead Aim (Have yet to complete this game on my own. I did play this game for over 3 hours and seen the rest of it on YouTube after finished borrowing it from a friend a little over a decade ago and I can say for sure that this game was a cool RE classic, except for some of its music, which I found it to be 5 times more repetitive than even most of RE2's as I felt like RE2 already had repetitive and out-of-loop melodies that were quite obvious to hear, but this game didn't bother to at least try to hide it at all. It has a story that tries to connect to RE1 but the new information we get out of it has little to no relevance in previous games. Atmosphere is great, at best. Gameplay felt weird but passable for at least trying out new ways, other than FCAs.)
20. RE Survivor (Extremely underrated for its setting and atmosphere for the fact that CV overshadowed this game for being part of an island and creepy atmosphere, surrounded by buildings used for experimenting on people. I see CV being a major improvement compared to this game but Survivor never got the credit it deserved for being the first in line to try out a couple of the new stuff that CV took the advantage of soon after. Gameplay is not that great and there were too many reused assets from past RE games, especially its enemy variety from RE2.
21. RE Survivor 2: Code Veronica (My least favorite in the classics era and has probably worse gameplay than the first Survivor game. Gameplay is choppy and the AI level you start with, is a total joke. Dialogue and translations are a mess and probably the worst there is in the series. It has a decent amount of replayability, but in order to play to its full potential, no lifing it is your only option with challenges that can be quite impossible to do because of its choppy gameplay. Quite fun in general but only if you are open minded about things like this.)
22. Umbrella Corps (This game isn't much of what you would expect in a 3rd person gameplay shooter but it is more or less fun to play, and again, with friends. It can get pretty boring after a while but the gameplay itself is just unfitting due to the character movements and animations that look a lot like if a group of fans tried to make a game but didn't know what they were trying to strive for. Aside from all this, it does offer some interesting background information, based on what has happened around the world after places like the Antarctic base, rural Spain, Kijuju, Lanshiang, etc... were decimated by BOWs.)
23. RE7 (Oh God where do I even start... this game was an abomination to the series as a whole, also because on how it even ended up as a mainstream numbered game for RE, instead of a spin-off like Gun Survivor 4 or a completely different title for its own universe or timeline. Protagonist was boring, no character development, terrible unoriginal plot and setting (e.g. ripoffs of Silent Hill 2, Evil Dead, Texas Chainsaw, Saw, etc..), useless and easy puzzles with no real meaning, no enemy variety, no real connection or mention from characters of any events regarding past titles, little to no replayability, generic RE-less horror atmosphere, anti-climatic final boss, and lots of other things that I rather not go into. It's a good generic horror game on its own, but as an RE game, it did extremely terrible and has little to no qualities about what makes up for a decent immersive RE tittle. A "return to its roots" does not mean that you need to sacrifice everything that makes up for a good RE game, just for the sake of having horror in it. The only thing that I still really love about the game is its main theme, Go Tell Aunt Rhody and a few characters; Lucas, Jack, and Zoe Baker. Other than that, the game can just burn and be forgotten in a void for all I care.)
In conclusion, almost every RE game are fun in their own ways. RE3 will always be my favorite RE of all time, unless a Remake is made for it and gets it right like RE2 Remake did for the original game. As I initially had a completely different opinion about RE7 before, I later came to realize that the amount of flaws that it has is much more bigger than a year's worth of grocery lists that I make for each week. It will forever be my least favorite RE game of all time.