Another useful consideration is overall size of the pick. I used to pick with Fender "Heavy" (can't recall the thickness). This one was ok, but the pick is small and it was hard to relax my grip - otherwise the pick would slip at the worst possible moment. This was especially true playing gigs outside in hot/humid weather.
Last year I visited Gelb Music in Redwood City, CA. They have an excellent selection of picks. Ed, their resident bass expert, recommended a pick made by "Cool" that is "Heavy / 1.0mm." It's about 1/3 larger in size and has a rubber insert. This combination of features makes it very easy to grip, easy to pick, and nearly impossible to slip. I haven't looked back. So +1 to the "try 'em and see what you like" philosophy.