I usually attak BUFF's with 2 IR Anab's and fire both at one target from a short range thats if am in a FLAGON.
I once had luck with Atoll-D I fired one from a very short range it went right into the left engine and BOOOM.... it splits the left wing and the BUFF went down in flame....!!!!
remember one thing u have to be really fast so the gunners wont get u, lock on the BUFF then fire from a close range so the missile seeker wont get fooled by the flares, aim for the inner engines not the tail so when it explodes it will make a huge damage to the wing this way u bring the BUFF down in a spin :D
Enjoy :)