I've had really good luck with these. They're tough, relatively comfortable, fit me well, and I can wear them for days. I can pick up tiny parts (eg, paper thin washers from caliper brakes) easily while wearing them.

But if I know I won't be working with any kind of chemicals -- rare -- I also have this kind and this kind. I love them, and they almost zero out the (non-winter) tendency toward sweaty hands, but they really aren't that protective from chemicals.