I just bought one of these and its been great so far..Easy to use and easy to adjust..Came with a nice 510 to ego adapter and a USB charging cord...The Eleaf I stick is also a popular 20w device...Both are considered really nice variable watt/ variable voltage boxes...I personally chose the MVP because of the longer battery life and the price i could get it for.
Pretty much any tank you want will work withing a limited ohm range...I prefer Kanger Protanks but many also like Aspire Nautilus tanks...Probably the most common tanks used as mentioned.
You will get quite a few different answers on tanks but ultimately its what you end up liking most..only way to do that is try them..Some are expensive and some arent but a higher price doesnt always mean youll like it better...its more of a preference thing.
If you havent already purchased an MVP20W and decide thats what you want, then look up EcigAvenue.com...Use code "20watt" at check out..i got mine for $31.99 shipped and delivered in 4 days ...They may still have them in stock..