What bout the iclear 30 or aga-t2? How do they fair against the protank? I currently have t2 and mini vivi.
Iclear is a dual-coil clearomizer and I personally don't care for them--long story. Rebuildables are a different animal altogether and not generally recommended for beginners--unless you are an electrician and a tinkerer.
I really like Kanger changeable coil clearos--you already own one, your T2 is a top coli model (so is your ViVi). I suggest you try Kanger T3--it's very similar to ProTank in design, if not identical, and can be had for a fraction of the price (5-6 bucks). Get some extra coils and play with it--if you like it, you can move on to ProTank. Just bear in mind that ProTank is not eGo threaded, is bigger and heavier than the T3 and generally better suited for bigger batteries (like the Vamo

).
APVs (AKA mods) are big and heavy and offer many features that small proprietary batteries do not. I suggest you visit our APV subforum and educate yourself before you make a decision to upgrade. Don't buy a mod (or anything else, for that matter) because somebody somewhere likes it). Read about prices, features, performance and reliability first.
That said, Vamo is a good choice, so is the Sigelei Zmax and eVic.
Good luck and happy vaping.