All three Panasonic 18650's from fasttech last a very long time. The gray ones and the two green ones. You would be hard pressed to go through two in a day with any of them.
If you really want to vape a long time between charges, The MVP will take you through two days and into the third. Its a great bang for the buck at 47.00 at Fasttech. You don't have to buy batteries or charger.
I prefer the SVD just because the way it feels in my hand and it looks great too.
I will be getting my Provari tomorrow. The only reason I ordered it is because I really cant understand how it could possibly better than my SVD, but after discussing with many veterans here, I just have to find out for myself.