Nintendo really got it right with the first games, Red and Blue. Since then they've added a feature here or there, refined the odd detail and added another gender as the protagonist, but basically the games haven't changed. I've only played two Pokemon games: Pokemon Red in 1996 and Pokemon Pearl in 2006. Despite the ten-year gap, they felt just the same. And somehow that's not a criticism - I'll buy the next one when it comes out.
I enjoyed the original game a bit more, but back then it was new and exciting and I was nowhere near puberty, so it's not necessarily better. The later ones are bigger, more colourful and have a bit more stuff in them. I'd say you're safe starting with any game in the series - although the first games and the most recent games do have the best starter pokemon [http://en.wikipedia.org/wiki/Gameplay_of_Pok%C3%A9mon#Starter_Pok.C3.A9mon].
Glitches are cool said:
It's easiest to go with the earliest, before all the wacked out mechanics of the game, such as EV, Hidden Power calculations, and a bunch of stuff that's unneeded to really enjoy the game, was put into said games.
I wouldn't worry about this OP. There's a system of behind-the-scenes stat modifiers, but if you just played the games without looking it up online you would honestly never know it existed. It's only relevant for competitive battling.
Though I haven't played them myself, it sounds like FireRed or LeafGreen are the way to go: all the best things about the original games with the benefits of GBA technology.