Well, here's what I think I know. We all know how fast Surfy is. We all know how fast Wally is.
As far as Waverider, I suppose I was always under the impression that his ability to move through time was based off his speed...but in reviewing some scans I have on hand...there is nothing stating as much. There is this:
Armageddon Inferno (92) 1.1 - Waverider a part of time stream.jpg
Pending something more concrete about Waverider, if what Pendaran says is true, then he (Nu Atom) is faster than everyone else here mentioned. Very interesting.
EDIT: I think I had this in mind when appraising Waverider's speed:
Zero Hour 4.5 - Wally moving at ultimate speed.jpg