Two balls I wouldn't normally suggest, but given what you are looking for: if you can find a Pearl Warlock DC, get it. Superflip. A ball that has a pearl coverstock and very high RG is the Killer Instinct. Very flippy if you have some speed. But surprisingly for me, the ball you might try is the Savage Flip, the first Ebonite ball I have seen I would have actually called flippy before I saw the Killer Pearl. Mediumish RG, high differential and it will flip.
What do I use for PURE flip? Vendetta or Thing Returns, drilled strong, a scuffed and lightly polished Voodoo (incredibly flippy with the coverstock). I also have just acquired a Killer Pearl, which is very flippy if thrown with speed.
--------------------
"I don't mind if you don't like my manners. I don't like them myself. They're pretty bad. I grieve over them on long winter evenings."