which resident evil should i buy?

Resident Evil Revelations is a pretty good game. I highly suggest this one if you like games in general. A note on the KB+M controls, if you get this one, you should definitely disable mouse smoothing/acceleration, whatever that option is in the menu. It makes mouse aim really awful.

RE6 may interest you if you want the RE universe but with much more action and not quite so scary.

I hear RE4 had a re-port so that the controls are better, but I may be wrong and it hasn't come out yet.

A lot of people say RE5 sucks, but I don't know anything more about it than hearsay.

I will recommend Resident Evil Revelations. It was great fun, enough so that I later purchased it for 3DS because I loved it so much.

6 is a regular action game with the series name and some familiar characters. Much of it is a standard third person shooter.

5 isn't quite as action heavy, but the AI partner kind of sucks, and currently co-op requires GfWL which can limit people to play with, though it is getting removed.

Operation Raccoon City is a okay L4D style game, but between the fact most people seem to dislike it and it uses GfWL (and isn't getting patched out), its difficult to find a full team. At least the AI isn't as bad as RE5. Most of the time anyway. Had to leave one behind since he would keep killing himself by running into flames to get enemies beyond them.

Resident Evil 4, I've never been a fan, though I do own it on PS2 and Gamecube.

RE4 and Revelations. I'm downloading RE4 right now. I'll tell you tomorrow if theres any problems with controls xd. Revelations is ok with mouse and keybord though :)

RE4 is my pick. RE5 is a coop shooter - much less scary - and without coop partner AI will turn you mad. RE6 has it ups and downs. I loved Leon campaign when Chris' campaign felt like CoD with zombies instead of russians/arabs. RE Revelations was not bad, had an oldschool feeling to it - but it was also a lazy port - graphics are on lvl of RE4 at most, map is TOTALLY UNUSABLE (maybe would make some sense on touch input but on PC it's garbage) and considering a lot of backtracking just to finish game it's a BIG problem and enemies are very limited and not very imaginative.

TL;DR: Single-Player: RE4>RE:Rev>RE6>RE5 for coop switch RE5 and 6 ;p

I'd say RE4 because it was the best RE, at the same time i'd get RE6 because the mercenaries mode in RE6 is awesome.

I had RE 4 on disk a few years ago so rebuying it now wouldn't be fun for me. 5 was bad. Revelations I couldn't get into. 6 I've always wanted but that DAMNED 30 CENTS is stopping me!

RE4, hands down. I also think it was the best RE game ever released. It plays perfectly with a controller (I prefer it), and it's spooky as anything. It's less creepy than Silent Hill 2, but for me it was one of those games that just sucked me in... as an adult. I don't think I would have enjoyed it as much when I was younger.

PSA: Play with headphones if anyone else in the house is nightmare prone. There's a scene that you will probably fail many times that has a lot of a certain female character screaming in a somewhat disturbing way. My wife, who thought FEAR was just entertaining, did NOT appreciate having to listen to RE4.

Ok, sometimes things work out in odd ways. I just had a friend, who has other friends, gift me the RE6 complete pack. And I didn't even ask him to gift me. He told me to take it. I tried to refuse but he wouldn't take it back.

Now I can get the cards and get RE4 HD.

I actually enjoyed playing most of em but go for Resident Evil 4 or Resident Evil Revelations!

that's awesome, thanks for the tips!

I played RE4 on wii. It used the wiimote really well.

As others have said, RE4 is the best of all RE games.