First off don't waste the extra cash on a digital volcano. The dial version works great. To smoke weed you want to start out at a 7 or a 7.5 and move up to 9 as the weed vapes out more. Also the non-digital volcano has 2 years more warranty coverage.
FOR THE LOVE OF GOD DON'T BUY THE EASY VALVE!!!!!!!!!!!
Get the solid valve. With the solid valve you can easily change the bags on you're own (making larger or smaller bags when need be). It only costs a few cents to replace the bags with the solid valve. Just buy the solid valve, it's what 90% of all volcano owners buy.
With the Easy valve the bag is attached to the mouth piece and is said to be non-user replaceable. So basically anytime you need a new bag (which you will every 2-3 months) you have to spend like 30-60 bucks to do so. Some people can change these bags but it's really a fucking pain in the ass.