Ah, I understand now. I'm referring to envelope weights as what you're referring to as influence volumes; i'm also referring to painted weights as what you're referring to as skinning weights. I don't want to come off as any type of smart alek, but I feel I should correct your terminology. Envelop weights are the ones that form a sort of "envelope" over the mesh where you can set the inner and outer influences. Painted weights is where you paint the geometry telling what bones to influence what.
As for what's better: Normally I tend to use painted weights. This is mainly because I feel I have much more control over the mesh this way, and envelope weights can be very difficult to form around a mesh sometimes. Still, painted weights can get confusing, and envelope weights are a bit easier to use. When using painted weights it can be difficult to paint exactly what you want when sometimes you'll accidentally paint something behind.
For a hand, I'd typically use painted weights, though others may use envelope weights. Really I feel it's more of an opinion on what works better, though sometimes envelop weights wont work. An example would be if you wanted a bone to influence the mouth of a character. An envelope would be very difficult to form perfectly around the jaw, while you could easily paint what you wanted to be affected.
Those are only my views on it, I'm not sure what other people feel.
