The very best MTL tank is probably a Kabuki from
House of Hybrids. They're pricey-- and then some-- but you'll have the best and won't need to replace it, probably not ever. They use commonly available Aspire Nautilus coils. I am not sure your model of Provari is so equipped, but the Kabuki is available P3 threaded specifically to fit Provaris and this will make a stronger tank connection than the standard 510 as the thread diameter is much larger. If you do not wish to blow the bucks on a Kabuki, take a look at an Aspire Nautilus. I think the Nauti X is the currently available model. They, of course, also use commonly available Aspire Nautilus coils. The tank is good gear from a reputable manufacturer, for all it is not a Kabuki. If you are a Protank type, you'll love either.
As to a new mod, what for? There are a bazillion mods out there, but practically any one of them would work for what you want to do as you won't be above 15 watts of power. That's peanuts; today's market has "small" mods from 50-75W max power. If 15 watts is enough, stay where you are. You have a Provari, and like it; doesn't get any better than that (and I can't believe I am trying to talk somebody out of buying another mod, sheesh!) If you just gotta, take a look at
Innokin. It's another reputable company, and they make tons of small mods with either fixed or removable batteries. Seriously, though, if you really want another mod, for backup or just because you want to switch off-- I do this all the time for no reason at all-- then haunt eBay or get verified and patrol the classified ads here and find you another used Provari. They do pop up from time to time.
Edit: Also pricey, but if you're looking for another "lifetime" mod, now Provari is no longer with us, you could do worse than a Dicodes. German manufactured, and all around superior gear.
Welcome to the board.