Generally speaking USSR tanks are easy mode (mostly brawlers), German tanks are normal mode (mostly snipers), US tanks are hardcore mode (nice guns on paper hull) and French tanks are guerrilla mode (hit&run, I call them my mobile artillery
).
Of course inside every nation you'll find up and down tanks but that's it.
I'd suggest to take it easy and learn one nation at a time. Explore each line (arty/TD/heavy/meds/scouts) and in the end you'll find something on your taste/style.
At lower tiers battles are intense and funny but once upping the tiers battles became more and more demanding.
Nowadays my major gripe is about teammates, it looks like they open wide the Zoo doors and every monkey is playing WoT.
Second came arty-party on high tiers so the game has almost no fun when you're nuked by 4-5 Tier 7/8 arty.
Third are some fundamental game bugs (like 0 damage crit hits and spotting system) but I can live with that.
Nevertheless the game is still fun for me despite all those flaws.