I'll have to play LoG sometime.
Anyway, my favorites:
Platinum enhanced: hack of platinum, the starters are Gible, Bagon and Dratini, fourth gen move split, greater difficulty.
Dark Rising: hack of Fire Red. Dark storyline, MUCH greater difficulty (but unlimited lucky eggs and 2 vs seekers). Starters Gible, Bagon and Dratini :/
Light Platinum: world championship, completely different world, insane variety of Pokemon, OH MY GOD THE FREEBIES, lots of stuff to do. Hack of Fire red.
Yet Another Firered Hack: a hack of Fire Red (duh) that doesn't get enough love, I think. 4th gen move split (anyone who does that gets my respect). I HAVE A METAGROSS AND A HYDREIGON AND- alright, alright.
Pokemon Team Rocket Edition: hack of Pokemon Red where you play as a team rocket grunt. Starters Koffing, Ekans and Meowth.