i had bridgestone potenzas non-RFT on a 2004 X3 and they lasted me about 22k miles before the tread started fraying. there was a whole website back then dedicated to trying to get BMW to replace them at no cost.
i also had bridgestone RFT on my current 2009 e90 and they lasted me about 26k miles
on the other hand on our 2009 X5 the michelins lasted us 34k miles.
i guess im speaking to the durability of the tires.
2012 335i ZSL, ZPP, ZPK, ZPS, etc
2012 X3 2.8i ZSP, ZPP, ZTP, ZCV, etc