I liked 4 a lot on the Wii, being able to use the Wiimote to aim was great. Haven't played 5 or 6, I heard they weren't very good. I have Revelations, but haven't gotten very far. Ditto to Zero on the GameCube, I need to beat that one so I can play Umbrella Chronicles without spoilers =|
I've beaten the DS version of the first game, and half of the DC version on the PSX (Jill, I think? The pre-Dual Shock version with the original soundtrack). Wish they had released it on the Dreamcast, because 2 and 3 on there were awesome.
Code Veronica was alright, but I wish I'd played it before Nemesis (as the creators intended), because it wasn't as good. I have the updated version on the GameCube, but haven't tried it yet. I'll have to use a walkthrough when I do, because I really hated when my character was carrying all of the good items, and then the game would unexpectedly make me switch to the other character (who didn't have much).
I liked that gun game that was on the PSX, too, I think it was called Survivor.
_________________
I'll brave the storm to come, for it surely looks like rain...