The Vamo is tried and true BUT quality is sub-par. The Zmax has HORRIBLE air flow. Just stay away from the SID... too many friends keep asking me to fix them. The Evic is nice but the software for it is a pain to get working correctly. Does the Provari do anything the others can't? Nope. But its build quality is the main factor. If you plan on vaping awhile and want a good quality APV the Provari is a good choice. Though the others are not bad choices it just depends if you like messing with your gear. You might also want to look at the Lavatube from Volcano... its build quality is superb and comes with a warranty AND does more than the Provari with variable wattage and a higher amp limit all while not costing as much too.
The LavaTube has never mowed my lawn. Just sayin'.