The larger bearings and shell size of BB30 and PF30 threadless bottom bracket systems are perhaps a bit more optimized for carbon frame construction, but you will then need to select a crank, bottom bracket and shell that are designed to be compatable with eachother. paragon offers some of these shells;
http://www.paragonmachineworks.com/c...&category=BB04

If you are using a conventional threaded british/ISO bottom bracket, then use a threaded 68mm shell;
http://www.cycle-frames.com/bicycle-...TTOM-BRACKETS/