Resident Evil 2: at the time it really was amazing, with multiple storylines, an appropriate creep factor, the first 'mercenaries' type minigame. So many other games built off that jumping point.
I realize this might be hard to do but if you can imagine what it was like to play RE2 for the first time, in a world where that was pushing technology, you can see how important the game is. Nothing against anyone's preference, of course but RE4 just doesn't exist without Resident Evil 2.
RE4 was the right game at the right time. After 4 original games + knock offs (Outbreak) and remakes, the formula was tired, the game stale. They turned the creepy haunted house feel into a crazy run and gun shooter (think the difference between Alien and Aliens) and after all that, did everything right.
Because make no mistake, RE4 is a monster of a game and from nearly every standpoint a better one than RE2 /except/ that because the gameplay became an entirely different beast, it's a bit unfair to compare the two. They're apples and juggernauts.
I voted for RE2, because I think that it needs to be remembered as a really fantastic piece of work, a landmark for it's day and I really do love the game. But I can't argue with RE4 as a selection either because it's equally as memorable and brilliant. It's just not the same game.
