I use Gloss-It EVP pad prime and love it, will never use QD or anything like that again. Makes the rotary just glide over the paint even easier, extends polish just a bit more to get great finish out of something like PowerFinish, lowers heat a but, but really helps keep the dusting down. All in all, that 4oz bottle will last me a heck of a time as I only need one little drop per panel.
I have used the following:
XMT Pad Cond
Menz Final Inspection
Water