I can't believe no one mentioned Jan Erik Liljeström, from the great ANEKDOTEN, his like Wetton and guys like whomever from Van Der Graaf Generator or Gentle Giant all mixed up with a great rockin', in your face style. Besides Squire, who is in my mind the definition by himself of prog bassist, I must say Wtton in RED surprises me every time a I pick up that King Crimson Record. All in all, every Crimson bass player (including our "cousin" Trey Gunn) have been amazing. And I could not let Sean Malone and Mick Karn pass like so. They are so great!! expressive, creative, unique sounding, great composers...
In the Chris Squire/ Geddy Lee/ Justin Chancellor debate: Squire is like The Iliad, all further epics come from that original one, or you saxon's Beowulf (the poem, not the CGI movie). Chancellor is becoming very fast into a sound reference, and a cult bearer. He must come forth with a project of his own, methinks.