For the BMI, you have a few options. You can run the AE 12L4 style front end it came with, the CRC front end, the Serpent front end, the old AE block front end (yes there are people that still like the old school front). All of them except the last one are basically the same thing and perform similarly.

I would stick with the stock front unless you want experiment with something truly different, in which case get the new BMI front end that's coming out. Completely different design.