I've had both an Evic and a VTR, unfortunately neither lasted very long for me.
I wasn't really impressed with the Evic honestly, it's pretty light and felt a bit cheap for it's price point. Now, if you like lighter devices, this might be an advantage. Either way, I was proven right as the top of mine started to crack and seperate, ultimately disconnecting the wiring, and I don't seem to be the only one this happened to. In terms of functionality, it has a lot to play around with the software and all, though I didn't really end up using it at all. Otherwise it performed fine and was quite fun to use.
The VTR is a really heavy mod and feels very sturdy. I picked it up specifically because I wanted a mod which wouldn't break as easily as my Evic. Also, because of it's form factor, it's a great fit for pockets, though it's a bit heavy for some. I can't use it anymore because nothing will tighten down on it and it's been giving me wrong resistance readings even before that happened. These are apparently common problems with the threading on the first wave and are supposedly fixed by now, but you might want to look into it. When it worked, it worked great though and I really love the feel of this thing in my hand.
The actual functionality is pretty similar, though the Evic has some advanced features like setting curves to alter the power output while you drag, which I found no use for, but maybe you will. If you are looking for power, the VTR has higher limits at 6V/15W vs. 5V/11W. And of yourse tube vs. box. Depends on what you want. If you're looking for a durable mod and don't mind the weight, I'd personally go for the VTR.