For me, it's more about the core-coverstock match-up. Both have to be there: I've had balls I haven't liked, and a new ball -- with the same core, but with a different cover -- has made a world of difference. Vice versa, too. A good cover, of course, is more important anyways (as it dictates a higher percentage of ball reaction by a fair degree).

In general, however, I've matched up to higher differential asymmetrical cores and lower differential symmetrical cores. There have been some exceptions, but that seems to hold pretty true across the board. The few high differential symmetrical cored balls I've thrown were very touchy, with a ton of over-under. The high diff. asymmetrical cores seem more continuous than their symmetrical brethren; but I do like the smooth roll I get from low diff. symmetrical cores. In either case, I also prefer a lower RG value. I've scored really well with balls that "lope"...but I've never felt comfortable with how they come off the spot. It's really hit or miss with higher RG values, so I pretty much stick with stuff that revs easier.

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