Someone on this board (don't remember who, unfortunately) likened the label
of Warp 10 as analogous to counting to infinity. We have the name and general concept of it, but actually counting to it can't be done because the scale keeps going up and up. You can always change labels and goalposts for new achievements in warp drive, but the concept of omnipresence via warp would remain the same and unreachable.
Thus it would seem that Transwarp/slipstream drive < Warp 10, only because Warp 10 is a concept and not an actual measure of speed, whereas transwarp/slipstream and I suppose even time travel can be measured. Things like Warp 13 are not concepts, but measures of speed -- less than omnipresence, but perhaps a more practical term. So to avoid confusion, the label and concept of Warp 10 should probably get a new name.