Welcome to the Newschoolers forums! You may read the forums as a guest, however you must be a registered member to post. Register to become a member today!
ABEC rating has absolutely NOTHING to do with bearing performance in any sort of skateboarding. The minute differences would only come into play at speeds upwards of like 100mph on 52mm skateboard wheels.
However, quality, and cleanliness do matter. Ceramic bearings have some small benefit, but i forget what.
Best bang for your buck? Daddies board shop bearings, something like $8, rubber seals, nice quality.
Clean them, and lube them, and all bearings will pretty much feel the same.