ZTs are funny beasts. I've got 4 of them now. The 0 452cf is a beautiful femme fatal. Sleek and dangerous in its graceful lines.
My 909 is a bruiser. Stout and robust and ready for the hardest of use.
My brand new 630 is the poster child of a mid size tactical folder. I'm not jazzed about tanto edges, so the up swept clip point suits my needs a little better. The wave feature is great, and I like how the G10 scale keeps it grippy in hand, but the titanium scale makes drawing it easier.
That said, after all that, the lowly 350st finds its way into my pocket most every work day. I've cut, scraped, lightly pryed and generally used it without regard to keeping it "nice".
The 909 is probably my favorite, but the 350 gets the most amount of hard use.