I found that the Shockabsorbers really chafed badly. My favourite is by Odlo, you can get them from Less Bounce. They're made of such soft fabric, there's nothing on them to chafe, and yet they're really supportive, (I'm a D cup).
Shock absorbers for me, I am an E cup (unfortunately) and although you can feel a bit like you are strapped in (the vest type) they are great. I wouldn't do any exercise without one.
(Oops sorry just realised this is rather an old post)
Still relevant though. I@m having trouble finding really comfy bras. Have just moved up from aDD to a G cup. Don't know why because I haven't put any weight on. I've got M&s at the minute which is quite comfy but having underwiring is something to get used to.
Shock Absorber for me but my local Matalan does a sports bra which are great also. They are the same design ect all that is different is the material, almost as good but cheaper.
I get mine from lessbounce.com but it has to be the Enell. Being rather large in the chest area, I need really good support and none of the other bra are comfortable while giving that support for things like running and horse riding.
I've been wearing the M&S high impact bras. I've found that a 32b isn't the easiest size to sho[ for at the best of times, but Marks are well stocked, offer really good support and wash well too.