What is the best premium tank in WoT?

VIII T26E5 - Probably the best all-around premium tank available right now when on sale. Workable turret armor, decent speed, excellent shell speed and penetration on the standard and premium APCR rounds.

What is the point of premium tanks in WoT?

While Premium tanks arent pay-to-win, they have some distinct advantages over free tanks that help them skip some of the grind associated with World of Tanks. These advantages include being able to train all sorts of crew , increased credit earnings, and preferential matchmaking.