I don't know about the others, but the TO800 is teh bomb, as the kids say. I've heard nothing but favorable things about the whole Behringer line from a sonic perspective. The only concern is their durability. Considering you can get three or four of them for the price of a "name" one, durability might not be that big of an issue.
Just realize that the TO800 IS a Tube Screamer clone. It does that very well. It gives that midrange boost that really helps a guitar cut through. It can get you on your way to an SRV tone. It is not a clean boost by any means. It will color your tone. For me and my purposes, that is A Good Thing and just what I was looking for. YMMV.
From what I understand, the Bad Monkey is basically a Tube Screamer with two tone controls.