I think full fingered offer more protection (especially if you're riding around trees / bushes / shrubs and of course in a fall, and mainly better grip (on the brake lever etc) particularly when your hands get sweaty.

I find the Troy Lee XC glove to be very good - breathable, not a huge amount of padding etc. My last set lasted 5yrs (probably 3yrs riding to be fair) and I recently upgraded to the new ones (same model). Something I did notice - having black gloves is hotter than say blue etc.