Help me choose which one of the three games i should get

[Killiana1a]

Depends on what you are looking for. I own Resident Evil 5 and it is your normal Resident Evil game where it is heavily linear and you are rewarded for how fast you beat the game. From friends, Final Fantasy 13 is great if you enjoy an epic story, linear gameplay, and the Final Fantasy battle system.

I can't speak for Heavy Rain, but I have heard it is mighty short.

I would have to vote for Resident Evil 5 because it follows a successful formula and offers satisfying zombie killing and the culmination from what happened in the original Resident Evil.