I like the Provari. Its a great device. There's plenty of VV devices out there now. I tend to think that selecting a VV or any APV depends more on the end users taste more than anything else.
If you like the box type mods, a Darwin, Opus, any of the plastic or wood box mods that take an 18500 or bigger battery and a Kick module will do. In tube style there are a bazillion different types.
If you want to narrow it down, you can cut the list pretty quick if you delete the Kick module. It's a fine item, but only goes up to 10 watts. It fits a lot of folks fine, just not so much for me. I put mine in the classifieds the other day.
If money is no object, then go with a Provari or Darwin. They both pack plenty of power and have an easy user interface.
If you're wanting a step down in price, the newer Lava tubes and Vmaxx. Good devices but they sacrifice quality for economy in a few areas. Not saying they're bad, just lower than the "Holy Grail" level.
If you don't want to blow a stack of cash on something without knowing if it will even be something you'll like, I'd say go with the eGo Twist. Doesn't get really up there voltage-wise but it does give you a good idea of what VV is all about. And it won't cost you a ton.
If you want higher voltages than the Twist, but still want it to be lower cost, there are quite a few vendors selling plastic VV box mods with displays. Not super durable, but many people report having good experiences with them.
In the end, it's really all about what you want. Review each need and find a device that gets the job done.