Well now you're going to have a real problem deciding what kind of vaporizers are good. You see I was trying to figure out what would meet your criteria and about the only thing I could think of was The DaVinci ascent. Since that's an older vaporizer I was debating even mentioning it.
I thought instead that I tell you the ones that are newer that I don't like or that I do like.
First off I think the haze vaporizer is a piece of s***. I had mine may be two weeks before I threw it away. The battery chargers are such a poor quality charger that I rapidly lost the ability to have any more than one use of a single battery. There is no thernal isolation like they talk about if you load one chamber with flowers by the time you vape that chamber the other chamber is going to be brown. I don't like being lied to when I purchase something. Both Chambers are quite small which makes it unsuitable for medical use in my opinion. They also claim the ability to switch between the cool convection draw and the warmer conduction draw. There is absolutely no temperature difference between either one.
Of the new vaporizers that I purchased I like the Pax 2 it's very small very, very stealth, easy to charge and has probably the largest bowl of all the portables I've tried that I've tried. The only drawback is it doesn't taste really great because of the metal chamber.
When I get the time I'll break down a list of what I tried and what I figure the benefits of each are. I will group them by entry-level mid-level and spending outrageously too much money.