this belongs in the apprentice forum I'm sure. and I don't know the answer anyway... Never had the chance to use one.
Volcano all the way man. Yes, they're insanely overpriced but it is the rolls-royce of vapes. I've tried many different brands and the volcano beats them all handily. Save up, it's worth it. Oh and get one off ebay if you can, you can get some really good deals on them.
My friend down the hall has a HerbalAir (sp?) vapourizer... it seems pretty legit - he said it was 300 bucks. I can always smell it though because I'm certain he always burns his bud. Smells like it in the hall all the time.