Ok, as a disclaimer, I am not a fan of FCA games,and whatever the hell umbrella corps is.
RE4 OG has it all, the atmosphere, the replayability etc. RE4R is a newer, rehashed and repolished version that encapsulates this perfectly. RE7 is great as a reboot and return to horror, eclipsing the atmosphere of RE4 even if the gameplay may not be up to par.
For A tier, good games, have some flaws. In the case of RE2R I've made my complaints known about the tyrant and the scenarios. In the case of revelations, I find the atmosphere in Claire's half of the levels pretty satisfying, if it wasn't limited by the nintendo 3ds format it was developed for it would be rated better, and of course gripes with the back and forth episodes. Village is close to 7, but is lacking in that oppressive atmosphere, but gains in depth and options for the gameplay. RE3R is arguably too short for it's own good, but I still like that it feels more fluid than RE2R.
B tier...Oh boy. I am not going to judge Requiem solely by Grace's part's , half of the game is just silly and derails the plot and lacks atmosphere. Even then it relies to much on that one section from RE8. Revelations 2.. IMO has originality gripes with The Evil Within, and to top it off the asymmetric "co-op" is annoying at times since the AI is not helpful. RE5....is fun, and arguably more consistent than anything bellow it. Lacks in horror, and generally pretty campy.
And C tier.....RE6 is too reliant on co-op, is too action oriented, is just terrible at times. The sole redeeming quality is taking the engine to the max, and Leon's campaign but just not enough. Untapped potential more like. RE ORC....I found it fun but generally too grindy, repetitive. Basically 3rd person left 4 dead. Also balancing issues. It is a lot less fun in Solo.