Ultex picks rock. I used to use Dunlop Tortex and Fender celluloid picks all the time.
I didn't realize how much better they were until my store ran out of them and I bought some Dunlop Tortex picks for the time being. The Tortex just don't have the same feeling, both in grip and in string feel.
They last forever, play well, provide good feel of the string, and great snap. That, and you don't need to replace them after every pick slide. They're also great if you use the edge of your pick to speed pick, as the edge lasts longer and doesn't seem to groove.
The only thing I absolutely hate about Ultex is the colour. When you drop a pick, they're really freakin' hard to find.
Edit: one more thing, the Tortex picks tend to warp and concave around the shape of my thumb, and the Fender pics rip/split in the middle, above my thumb; they Ultex pics have done niether (so far).
