I'm sort of stuck here. I am no pro, wanted a dSLR for the features and quality I could achieve. This is just another hobby for me and I cannot justify owning 5 lenses... YET. Anyway, I have the kit lens (18-55) on my t1i, but want something sharper or faster or more versatile (or all of the above?) The new 15-85 really fits the versatile bill here, and I have read some good stuff about the IQ. The 17-50 f/2.8 Sigma or Tamron, I don't recall right now, but either way I have heard good things about that lens (mostly), and the price is very attractive as well. I have considered the 24-70, or 28-75 f/2.8, but would like something a little wider (I think!) My idea here is to minimize swapping lenses, but keep a certain level of quality. The 18-200 fell out of this comparison due to pretty bad reviews on IQ, what else can you expect with such a long focal range. I wish the 15-85 was a constant f/2.8, but I'd be spending twice as much. I know I know, I want too much from one lens, but whos to stop me from dreaming. This all lays out like this, if I get the 15-85 I will probably almost never need a tele, but will have a "slower" lens (I do a lot of indoors). If I get the 17-50 I get the speed, possibly IQ, but lose out on the wide end AND the long end. The 24-70... I lose a LOT on the wide end. Does anyone recommend the 18-135? I'd give up speed if the IQ is up to par w/ this lens.