[WoT] A Fun Tank To Play

Tanks and their are a substantial part of WoT gameplay. No doubt.

What tanks are fun for you and what are not? And most importantly - why so?
What makes fun tank gameplay for you and what breaks it?
Do you feel like there are enough unique tanks in the game that can boast their character, or the game is trending towards average-like vehicles lacking in character?

Any vehicle-tank-specs-related thoughts will do.