Started with Gen 1, Yellow version, although I never got past Lorelei, because I was really stupid and ditched my Pikachu for a Graveller and never thought to use anything but Graveller. . . it took me forever to beat Erika. xD
After that, I played either Blue or Red, can't remember which, then Gold version -- where I never even got to Red -- and then onto Ruby and Sapphire, since I got both. And then FireRed, and Emerald when that came out. And of course, Platinum. Still need SS and Black version, though. :U And Black/White 2 of course.
Started with Gen I on Red. My favorite gen is likely II or IV, but I really love plenty of Pokemon from all gens. I hate plenty others too. My favorite game, I think, is Emerald or SoulSilver. I have trouble deciding. Maybe Crystal. --- My spell check just had a mental breakdown... White 2 FC: 3139-4385-8079