For me, it is Pearl.
I had played all the previous games (and I've since played all the games following it), but back when I played Pearl, which was back when I joined the forum originally, I was so completely immersed in Pokemon...it was just so fun! I mean, it still is fun, and I'm still really immersed in it, but that was the first time I had been able to play with other people wirelessly around the world...and I thought that was WILD! Sinnoh is my favorite region, from the games, to the Pokemon, to the anime!
I had played all the previous games (and I've since played all the games following it), but back when I played Pearl, which was back when I joined the forum originally, I was so completely immersed in Pokemon...it was just so fun! I mean, it still is fun, and I'm still really immersed in it, but that was the first time I had been able to play with other people wirelessly around the world...and I thought that was WILD! Sinnoh is my favorite region, from the games, to the Pokemon, to the anime!