I haven't handled anything from their Fusion line. However, I've played with several of their other knives and I own one of the Spec-Elites (posted a review of this one a while back) and have been pretty impressed with them.
I would look at either a Spec-Elite I, the Trident, or any of the models with the Arc-lock. Many of them can be found for a reasonable price on some of the internet knife stores or on e-bay.