I'm after more flavor in a
tank. The best low cost tank I've vaped is the Evod TS3. There's a noticeable difference in flavor between it and the original Protank. My zero point reference is the SmokTech Mega SS carto.
The are all great the first day or so and then the coil tends to coat and the great flavor dies. Rebuilding the coils is a little of a pain, but I do that to subsidize the cost of just buying a new 5 pack. I find that it's not so much a pain if I sit in front of the TV and do it in mass production mode.
I like the thick pyrex glass on the Protank. I'm done with plastic and polycarbonate (which is still plastic). My original Protank with the Pyrex glass has dropped a number of times on concrete with no cracks, although you can see dings and scratches on the metal ends. I guess the thickness of the metal caps prevents direct contact between the glass and the concrete. You can't even find a chip on the pyrex.
If I changed the head every morning on the Protank, it would be my favorite tank for flavor and vapor. The Evod TS3 seems to hold flavor longer on a head. That's kind of strange since the heads are very similar.