Those are two of my favorite balls. I guess if I was looking for a heavier oil ball I'd go with the Revs. If I was looking for a medium I'd go with the Ultra. I don't think you can go wrong with either one honestly. I am absolutely in love with the EnMotion coverstock. It gives a nice read without being too skid/flippy, and it is easily adjustable. I like the cover on the Revs for the same reasons except I think it can handle more oil than the Ultra especially if the back is dry.
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Equipment in Bag:TZone, Cell, Awesome Revs, Awesome Finish, Twisted Fury
Not in Bag: Fury x2, Fury Pearl TE, Rock On!, LT48