i'm gonna be open and say the only binder i could wear 24/7 with zero discomfort (even compared to just wearing a loose bra, sports bra or nothing) is this one:
http://www.lesloveboat.com/shop/product_info.php?cPath=52_56&products_id=124&osCsid=d59da0733a4cc15a0cc7000cc774c257 there are some binders by the double collection which also look like they should be really comfortable but i haven't tried any of them. from those i tried so far, this is my personal comfort chart:
1. juya sports pullover binder (i sleep in it)
2. esha extra strength long binder after cutting it into a short binder (different cut from the short binder, t-back doesn't weigh down my shoulders)
3. esha extra strength short binder (t-back not too comfortable for my shoulders, apart from that really comfortable binder)
4. t-kingdom m1700 (the binding material may be a little coarse, kinda like bandage, but it's overall quite comfortable, you gotta give it that. other than that, it's ridiculously overpriced because the material compares to the next binder i'm listing, and it creates cleavage and side boobs even though my moobs are only like a 32A or small B)
4. Double Collection Sports Bandage Velcro Short Binder (material not as soft, more like ace bandages in the front; shoulder straps and back really soft and comfy; bottom seam may cut in a little)
5. Danae short binders (comfortable to wear but material not really soft; may constrict your breathing without you noticing...i only noticed a lack of energy at times when wearing it, and when i took it off i realized it was because of the binder; same happened to me with underworks binders)
6. a little girls lycra spaghetti top (spaghetti straps did cut in)
7. underworks binders (material really rough+ coarse, may bruise, cut in, cause chaffing, wouldnt lay flat at the top)
...of course that's just my personal hitlist.