I have owned several vaporizers, and I can advice you on this. I would stay away from the box style vaporizers, and go for a "Arizer V-tower" vaporizer. It has some advantages such as durability, accuracy, quick heating time, and a lot of vapor with each drag. It also has lifetime warranty.
They have two models, one with air assist and one without. In my experience, the cheaper model is actually more efficient. Good luck,
Max