There is the standard SRAM GXP BB (with steel bearings), then there is the overly expensive model by SRAM with ceramic bearings (marketing as part of the Red groupset I believe). There are not many options from other manufacturers, but I've been very happy using one by Hope - they make external BBs that are compatible with Shimano's HTII, but you can use one of these with some added sleeves in the non-drive side cup to make it compatible with SRAM's GXP, which Hope makes exactly for this purpose. I've been running this setup for over a year and am very happy. The bearings are stainless steel, and the crank spins exceptionally smoothly (much more so than any of the standard Shimano HTII BBs that I've worked on). I swap cranks around quite frequently (I have three SRAM and Truvativ cranks mounted with 33/48, 28/46, and 26/38/49 chainrings that I switch between depending on the terrain and speed of the ride) and have never had a problem with any crank coming loose after torquing it to the recommend spec' with the well-priced Park Tool beam-type torque wrench.