Object 252U
Or its Defender variant. The Object 252U is a semi-recent addition to the game, and makes for one of the best Premium Tanks in World of Tanks.
A combination of decent mobility and substantially thick armor will always make for an effective mix. The pike nose design allows for maximum possible effective armor thickness without having to slow your vehicle down too much or worry about angling. Add an 440 alpha damage 122mm main armament with decent DPM to that, and you have a force to be reckoned with.