I can't say I have a single 'best vape' purchase. I own or have owned some excellent models, and my favorite depends on my mood or requirement at the time. The worst would be my first- a BC Vaporizer purchased due to insufficient research (and a general lack of good internet info at the time) and sticker shock at the price of vaporizers. The BC design (along with the other 'conduction dome vapes') is a poor one and only my desperate need to avoid smoke kept me in the vape market. The BC could also be said to be my best purchase as well, in that the decision to buy a vape, any vape, was the best mj related decision I've ever made.
Let's keep this thread on topic and away from vape shopping. If you're going to ask a question about someone's choice(s), make sure you've listed your own first, and ongoing discussions about what to buy are off topic. If you've only bought one vape you don't really qualify to post, and you should list at least your best or worst, if not both.