I like Fox knives, but in this case I'd go with the Spyderco. You get much better steel (S30V versus 440C) and an overall beefier (and larger) knife. Fox linerlocks have earned my respect (I've seen a Folgore take serious abuse, and my Pro Hunter works flawlessly), but I still like the ball bearing lock better.
If you can get your hands on any of the flat ground versions of the Manix 2 (whether it's one of the sprints or the light weight version), buy one of those. I think they are much better than the regular Manix 2, I'm not that fond of the hollow ground blade, and I think it can be made lighter without sacrificing strength (my S90V Manix 2, with its FFG blade and lightened liners gets a lot more use than my regular Manux 2).