Jack Bruce. Period. His bass playing on the live track "Spoonful" from Cream's "Wheels of Fire" album recorded in early 1968 in San Francisco is the very best bass performance ever from a rock band in the 20th Century. Can't touch it. A monumental masterpiece. A damn good runner up is John Entwistle's bass playing with the WHO on the "Live at Leeds" album from 1970.
Best rock bass player
Today is the 11th anniversary of John Entwistle's death. I had the pleasure of seeing him play live a few times and was always impressed by his musicality and ability to keep up with Keith Moon- much less lay a foundation for Pete Townshend. I also have always enjoyed Chris Squire, Stanley Clarke, and Flea for similar reasons. Who are some of your favorites?