I've played through and own every title from 0 to 5 (every on of the good ones, anyway). Code Veronica is my favorite, followed by 4, then 2. What made Code Veronica so memorable was the characters with ACTUAL CHARACTER DEVELOPMENT, an original and interesting plot with twists that weren't bullshitty "support character A was evil all along" cockslaps, and of course, it was the title that brought Albert Wesker back into the fold...so that he could be pointlessly killed off in a weak-ass finale to a limp-wristed attempt at mimicking RE4's glory after showing up as a behind-the-scenes support character and recurring villain for a few games. But still, playing through that game for the first time with no knowledge of Wesker's survival, Wesker showing up and kicking the shit out of Chris' sister with new, mutation-based superpowers was a pants-shittingly awesome twist. And there are even better ones than that. Also, it has a death scene where I was actually moved to feelings of pity and sadness, the first time a game has ever affected me emotionally on such a level.