+1 for BB7 disc - I have switched out all my hydros on all my bikes for Avid BB7. The ease of set up and they just plain work. cheap too. pad replacement and realignment is a breeze for me.
Easy to swap between bikes just need a new cable for the rear.
I got the 180mm rotor on the front of my nice mountain bike with 5+" of travel front and rear- it works even better.