The M-18 gets great reviews but I've hav'nt handled one enough to recommend it.
Otherwise:
The Walker Bladelock is the king of the CRKT knives (IMHO). The only drawbacks are the AUS-6 steel (which is'nt really as bad as some would have you believe) and it is abit heavy (just over 4 oz).
Personally, I think the locking mechanism is terrific (although it does take a little practice), and the fit-and-finish is almost flawless on mine.
Truly, the only reason I don't carry mine is because of the weight. I prefer lighter-weight knives (Endura, Air Ranger, Calypso Jr, ect).
The #2 CRKT knife, IMHO, is the large Mirage. A very stout and extremly comfortable knife.
For the most wicked looking CRKT, check out the Seahawk II.
Good luck,
Allen.