Best rock bass player

Have to give the nod to Tony Levin for his work with King Crimson especially. Also John Wetton and Chris Squire are "musts" for this list. Possibly the greatest bass player that gets very little recognition but is immensely prolific is Mr. Leland Sklar.

Falconquest,
All worthy choices. Each great in his own way.

Honorable mention for Dee Murray of Elton John's classic band.

a couple not mentioned above whom i've always admired:
graham maby (joe jackson, freedy johnson et al)--a really lyrical player who really frames some excellent-sounding records. i have a special weakness for him cause he also played with they might be giants, the only palatable children's music ever
cris curtwood (meat puppets)--in their very brief heyday they were the best band in america, and he swung like a mofo. i understand he because a serious, dysfunctional junkie, but "up on the sun" is as good as brainfry gets

Loomis,
I actually mentioned Graham Maby as one of my favorites much earlier in this thread. He has a great bouncy, percussive and energetic feel in his playing.