Actually the current Legion is really the only one I've ever known. I never got into comics before Crisis and all the subsequent reboots (apart from a few comics I'd get occasionally as a kid) so the first I really knew about them was at the start of Legion Lost. In fact the only reason i even read that was because of the LMBP.
Anyhoo, how to sell you on them. Hmmm. Well it kinda depends on what comics you like anyway (kinda goes without saying, but never mind) but to me it's actually pretty much a fun comic. OK that's not exactly the most effulgent praise ever but it's what I want sometimes. It's got a big cast, loads of different types, no players really that much more important than others (unlike groups like JLA or Avengers or whatever) and they're off doing all heroic things in a big wierd futuristic world. Kinda the same reason I love JSA. We're not dealing with big philosophical questions or anything, it's just superhero comics at their best.
Plus there's the art. I love Coipel and I'm loving Batista now.