You need to earn your stripes as it were in the lower tiers to get up to decent levels/tanks.
Everything has its strengths and weaknesses.
Scouts are fast but have no armor or decent guns for the most part.
Mediums have decent everything but cant handle heavies and can be exploited by scouts if the scout knows what he is doing.
Heavies have killer armor and guns but are ponderous on the field and can be exploited by fast tanks.
There are trees for self-propelled ATGs as well. Some like the early German ones like the Marders, have good guns but no armor. Then you have excellent ones like the Hetzer, Stug & PzIV/70 just to name a few.
Then you have the dreaded self-propelled arty. Everyone hates these guys. You can be killed by someone hiding on the back of the map. This is why you always have to be moving all the time. Arty almost always has no armor to speak of, but can kill with indirect fire.
You have all these trees to work on in each of these different countries -
America, Germany, Russia, Britian, France, China
Its a lot of fun.
__________________
|