I personally like green stuff the most. You can mix up very small amounts in order to keep each sculpting session short.
I have used super sculpey before, but I have found some difficulties with it (maybe it\'s just me, but who knows?). I found that it doesnt stick very well to plastic and metal miniatures, so converting with it is probably not a good idea, especially if it\'s on a plastic model, you wouldnt want to bake that! lol
In your case I would use some kind of epoxy putty, that way you can mix up small batches to keep sculpting sessions short and eliminate waste.
-Matt