The Invisibles is different from Invincible. Invisibles is a trippy vertigo book by Grant Morrison, Invincible is good old fashioned fun superheroics. The hardcover is definitely the way to go with it though. If you just read the first and second soft cover, you might still think it's lame, but by the time you get to the third one you'll be on the edge of your seat. (The hardcover contains the first three softcovers). Fables is the most satisfying read out there, so I definitely say pick that one back up.
52 is good if you're a big DC, it juggles alot of stories at once but there's not alot of focus on more major characters.
They canceled Green Arrow and have relaunched it as Black Canary and Green Arrow, which Winnick is still writing.
The big thing with GL right now is the Sinestro Corps story arc. That'll be together in trade in a few months and is well worth getting (I assume you read GL: Rebirth, right?)