Unlike most people, I don't mind old threads being bumped. It may be against the rules in many places or at least taboo, but I think it's better than making a brand new thread when a perfectly fine thread already exists..
The Master of Mario, you made a few good points on why Mario's ground game is better than Luigi's. I'd like to point out that Luigi's Cyclone has disjointed hitboxes, though, so saying he has zero disjointed hitboxes is incorrect. Also, I'll point out that Luigi will
autocancel 8 shorthop double aerials... EIGHT! Luigi autocancels better than Mario; not the other way around.
Anyway, plenty of people have already said what I wanted to say (double aerials, KO potential, etc.) except for one thing:
THE JAB!...
No character has a quicker jab than Luigi's Jab. It's second to none in terms of how quick it comes out. Due to the quickness of it and the speed/power (yet close range) of his other attacks,
Jab1 followup combos are killer. Mmmm... Jabs.