Not to ask too personal a question, but i think it kind of depends if you're you having a lumpectomy or mastectomy, and are you talking about a bra to hold a form to give you back shape?
I've seen the ones in M&S and they have pockets for forms, which you can get in different shapes to suit what you need.
Someone recommended a brand called Evenly.
If you just mean a decent comfortable bra, then can't really go wrong with an M&S tshirt bra. I got a back of 3 without underwiring, nice wide back, nice thick straps!
