I have 11 Ibtanks, 1 Prive Special, 1 Phiniac, 1 Loki Tank. I leave about half of the tanks at office and the other half at home.
On my Provari, favorite is Prive Special, and only because I don't have to mess with Pro-Ring or Hippo to get that flush look (a big deal to me) . Otherwise I would rate it last due to its PMMA tube (I prefer Pyrex glass) and frosted finish (I prefer clear).
2nd favorite would be IBtanks (actually my #1 favorite when I'm using my other PV such as SVD & EVIC). Should be obvious since most of my tanks are from them. lol. Very good quality and very affordable.
3rd would be Loki Tank because of its slots on bottom cap for air flow on Provari.
Last would be Phiniac. I do like it and use it daily, but if I"m in the market for new tank now, the priority would go to one of the three above.