I haven't tried an Innokin tank yet, from the looks I'm sure it's better and quite different from the Protank heads I've been used to. I had an SVD, my only complaint was it's extreme height in 18650 mode. It performed great, it was just too tall for me. I bet the MVP and VTR would be just the size I'm looking for. From the stories and reviews, the MVP is built to last. The VTR looks even sturdier, I would love to give one a try.
Why I like Innokin: The SVD I had seemed to put out cleaner/stronger power than a VAMO. Don't quote me as I may have my facts wrong, but I heard some Innokin products (specifically the MVP) use a higher frequency than most PWM's, something like 100 instead of 33.3. This would make for smoother coil heating, less spikes, and less of a "rattle snake" effect. I could be wrong, I thought I read that about them a few times, but certainly can't test that myself. In any case, I would love to upgrade from the standard 33.3 PWM chips.