The brake setup on ther right now is an Avid Juicy 5. It will soon be a Hope Trials Disk though. (It was leaking when it showed up so I put my XC hydro disk on there temporarily.) IMO Hayes have a little stronger lever feel but I like the modulation of the Avid's. Hayes are also a little easier to re-bleed. Pretty much whichever you can get for a good price. (Juicy 5 from Avid or HFX-9 from Hayes are both pretty affordable.)

Dan