C. Henry is who I would pick. he's definitely the WR3, so there's not really a gamble in that sense. But as the WR3, there is still some risk that he won't get enough playing time. I think he will be on the field a lot, since Carson Palmer is back and the Bengals running game is still pretty mediocre. I'm really just guessing about his playing time, but I still rank him #1 because even if I'm wrong and he doesn't get a lot of snaps, he's tall and a big TD threat. The Bengals should be able to get inside Denver's 30 or 20 yard line a few times, and Chris Henry becomes much more dangerous once they're close.
E. Bennett would be my 2nd choice. True, GB has a good pass D, but I don't think the matchup is as bad as it looks on paper. Al Harris (CB) will probably be the guy defending Bennett's side of the field. Harris is a decent cover CB, but is apparently not adjusting well to GB's new zone D, not to mention he's getting old. Bennett is also almost certainly going to get more playing time than any of your other options. If Green Bay gets a decent lead, the Bears will have to pass more often... good news for Bennett's fantasy value. Probably a safer pick than Henry, but probably not as much upside.
L. McCoy probably has the most upside, but I rank him 3rd because I'm guessing that the split won't be anywhere near 50/50. I agree that it's a good matchup, but McCoy could end up sitting on the bench most of the time, and I think your other options are good enough that he isn't worth the risk.
I like your other 2 guys for their potential this season, but I think you're right to sit them for now.