The Trifecta
I own an Arizer Solo. Not the new model but the one that won't charge and operate simultaneously. I also own a Da Vinci Ascent and a Pax Ploom. I like all three of them.
1. Arizer Solo - Not the most portable because of the detachable glass mouthpiece. Doesn't have the LCD screen with precision temperature control and programmable sessions of the Ascent. But, this has the best vapor hands down. I bought a case for this just so I could haul it around with me in the car. With improved airflow and the charging oddity removed, oh and the better price I really believe that overall the Solo is the best vaporizer out there. Also, my Solo has been used thoroughly for over a year and it still cranks.
Now there are reasons you may prefer the other two...
2. Da Vinci Ascent - Ultimate control over temp, and once you get the hang of it the programmable sessions are very usable. I also like that it has a movement detector so if you're spacing out... it shuts down. The Solo works off of a set timer. Also, with the embedded mouthpiece and a chamber that is quite a bit larger than the Solo's I do believe this scores a bit higher in the portability category. But, the vapes just aren't as smooth and tasty as the Solo, so I often find myself going back to the Solo unless it's impossible for me to take it where I'm going. I also had an Ascent shit out on me after one month of use, stopped charging. I bought it off of eBay and the company refused to honor the warranty. I was disappointed.
On a sort of side note. I think that a combination of these two vaporizer would be glorious. The built in mouthpiece and the digital temp controls of the Ascent, but like the Solo the herb should be put into the mouthpiece and not placed in the cooker itself. I believe that's why the Solo is so smooth. Convection over combustion or whatever.
3. Pax Ploom - Honestly, the Pax Ploom is cool as hell because it is SO portable. When you get it you can't help but love its small but sturdy design. It's simple but effective. And, like I said this thing is impossibly small and still has a pretty huge chamber. But, I find that it's vapes are the worst of the three. They're still good, don't get me wrong, but the taste and smoothness just isn't there.
Overall, I'm about to use the Solo right now and that's usually the case. But, I would still recommend looking at an Ascent or Ploom in the future if concealment (concerts,etc) is an issue. It's just not convenient hauling around a separate glass tube that is liable to break. I've broken one of the two stems that it comes with already. But still, I love the exceptionally tasty and huge vapes I get from my Solo, I've been quite close to buying the new model several times.
EDIT: Although some people avoid it... eBay is an excellent place to buy vapes. They usually come with a case or grinder at a better price. $130 free shipping right now I believe.