they are both 'good'. but they have different applications. For instance the air still is not for making vast quanitities of the stuff. It is for making 5 or so liters at a time for people with limited space available.

The water stills, in particualr the larger 25 liter stilsl will produce a lot more alcohol and do it quicker.

if u live in a unit then the air still would be great and if you dont want to spend a lot of money then they are good. You get what you pay for though and the bigger still do a much better job