I really love Gen II (especially the remakes) because of the little Pokemon following you around everywhere. It made me care about them, though, and meant that I ended up spending a lot of money and time to make sure they were happy and not hurting or anything. Increased character caring potential way up in those games and I'd love to see that feature in other game in the series. Plus, the touch interface is probably the best in all the games period. So simple and convenient to use and don't have to hold anything down to run. Tapping the bike to go places...etc. Just wonderful... Then the story. That was brilliant too.
Then the storyline, the introduction of two new types (steel and dark), and many of the Pokemon in generation two are my favorites as well. Like the Togepi line. So adorable. Yeah, I'm a gen II gal all the way...xD