Never used a volcano but like most things I buy I researched it first and the reviews said it was better than the volcano because you can do bags and hit the whip directly. Where as the volcano only does bags. The volcano was 500$ when I bought my first airizer for 140$, 3 +years later my airizer still works like day one and I liked it so much I bought another newer version and have been using it along next to my other for around a year.
I turn it on in the morning and it stays on all day most days. I have tramatic brain injuries and its the only way I can get my brain to work.