As Tysilio said, lots of binder review threads out there. I like the idea of this one as a catch-all though. My contributions:
Underworks 997http://www.underworks.com/men/compression-shirts/ultimate-chest-binder-tankComfort 0/5: 4
Effectiveness 0/5: 4
Discreetness 0/5: 5
Overall 0/5: 4
Rating: This is the most comfortable binder that I own, provided you get it in the correct size. It flattens my chest very well, though you have to do some minor adjustment to reach an optimal flatness level. Very discreet. It flattens and smooths out your entire torso, and really just looks like a tight undershirt if someone sees it. I recommend wearing an undershirt above the binder but below your top layer of clothing (so skin->binder->undershirt->top shirt) to minimize any weird lines you might see. I only rate it a 4/5 because it tends to roll up at the bottom, which makes it inconvenient for active wear.
Underworks Tri-tophttp://www.underworks.com/men/compression-shirts/tri-top-chest-binderComfort 0/5: 4
Effectiveness 0/5: 5
Discreetness 0/5: 5
Overall 0/5: 4.5
Rating: Not as comfortable as the full tanktop style, but I think it does a better job of binding the chest after you adjust yourself. I've noticed that mine is comfortable everywhere except in the armpit area. For whatever reason it tends to really rub there on me. I think these tend to work best and be the most comfortable choice for thinner people - since it only comes up to the bust line, it can make your chest look thinner and your stomach area larger. Kind of like you're wearing an innertube if you're a bigger guy. Aside from that, I think it's pretty discreet unless that's all you're wearing. Then it looks very odd. I experience a tiny bit of rolling up with this style, but I find that it's much better to wear if you're going to be moving around.
