If you've got a taste for retro gaming, I think you'd enjoy RBY and GSC a lot - especially the latter, which has held up much better. It's still a terrific game, and it's surprisingly nice to look at too.
RBY is definitely more dated in many respects. The AI is downright braindead at times, Psychic-types are overpowered, and the graphics - while solid for their time - are practically avant-garde in today's day and age. Depending on your sense of humor, though, the visual style might be a good thing; I know it is for me! On the bright side, the soundtrack is still excellent, and the gameplay is very fun. Compared to the rest of the series, it feels pretty offbeat and low-budget, and it's fascinating how such a lovably unpolished game became an ultra-slick, blockbuster franchise.
All things considered, I do think RBY is a great starting point; it's an interesting piece of history, if nothing else. If you really don't dig retro gaming, though, HeartGold/SoulSilver is probably the apex of the series, and I'd go with that.
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Hey, you ever coming back?
You kidding? I am Queens Boulevard.