Goodness, you guys have been bringing out my inner nerd between Comic books and pokemon XD.
Obvious yellow version, if only because that is literally a chunk of my childhood.
I loved the Firered remakes. Crystal was awesome, first time the pokemon moved when they appeared in battle (plus choice of trainer gender). Heartgold/soulsilver because it brought back Yellow with the pokemon walking you(Yes, I am so sentimental and I get SUPER attached to my pokemon).
I also loved Black/White and can't wait for Black2/White2 to come out. I don't know why people who have been playing pokemon since the very first game would complain about it. I mean, it really took everything to the next level. The pokemon move constantly and have correct size comparisons. The story was original and intriguing! And I loved the new pokemon. Especially Deino, it was just so cute!
Honestly, I love all the pokemon games. And I won't lie, I play them on my PC now because I was such a freak about restarting games that I never restarted, like ever. So now I can have infinite saves without losing my precious pokemon XD