Heya, and welcome to /r/ArmoredWarfare.
A few quick things first:
RNG world of real-life tank warfare
RNG plays a much smaller role in AW. It's there, but it's no where near the head-scratching RNG of World of Tanks where you'll bounce sure-penetration shots or watch shells fly out of your cannon at 15° angles when fully aimed in. Even damage wise, you know what to expect with each shot (depending on what part you hit¹) so it's a much more straight-forward approach.
I'm familiar with the grind (possible turn off but we'll see)
The grind is also not as bad in AW. Getting to Tier V is pretty simple, and only then do you start to notice the slow-down, but it's still not the same fun-vacuum that WoT made it. If you're a decent player with Premium, you can expect to unlock about one module a day with an hour or so play session. For reference, I just purchased the Tier X XM1A3 earlier this week and with Premium, Maxmillian as my commander (10% rep bonus) and running some of the single-use reputation boosts, was able to unlock the 140mm gun for ~135,000 Rep in one night through Hard PvE missions.
Now, on to the question at hand:
In Armored Warfare, there are MBTs, and there is everything else. I don't mean 'everything else' as a pejorative, because they are certainly capable, but your role on the battlefield is dictated by what you're driving: MBTs take objectives, other vehicles support them². I'll give you a quick rundown of how each of the lines plays, and some suggestions towards the end.
Main Battle Tanks
Most important things for MBTs are the trifecta of Offense, Defense and Mobility. Here's how they all stack up.
East European MBTs (Russian line)
All about single-shot alpha damage. Huge damage numbers with slow reloads (think Sheridan, since you said you have that unlocked). Maximize your damage with retrofits, load up on HEAT and aim for weak spots and by Tier VIII you'll be blasting people for well over 1,000 damage per shot. Well-rounded turrets are pretty bouncy, but the hull is just okay (but usually covered in ERA which helps a bit). Pretty middle of the road as far as maneuverability goes; a little sluggish from a dead-stop, but once moving they are alright.
West European MBTs (British/Italian line)
Essentially the polar opposite of the RU line. Probably the lowest damage of all the MBT lines with an average reload speed. Easily the slowest MBT line in the game, right there next to Artillery. Dat armor tho... You're a moving fortress and can pretty much laugh at anything trying to shoot you with less than a 100mm gun. The Tier VII Challenger 1 has 676mm of turret armor and 550mm of hull armor.
Leopard Variant MBTs (German/Italian line) This line is interesting. Tiers III through VI, you play more like a light tank line. Better than average firepower and maneuverability, pretty bad armor. Play these as a support tank and you should do just fine. At Tier VII, things change, and your turret armor becomes monsterous. If you know the map and know where you can hide hull-down and show only your turret, you will do fine. Easily the most maneuverable of the MBT lines, even at high Tiers. Fire from cover exposing just your turret, scoot forward to new cover to push the fight.
American MBTs
You knew the phrase was coming, so here it is: Jack of all trades; Master of none. They do everything well, but nothing great. The driver's hatch on the front is a big weakspot, however weak spots are due to change in patch 0.18. In PvE, the weakspot isn't that bad, as enemy AI aims for 'center mass' and you can use that to your advantage, but in PvP, the hatch is a giant SHOOT HERE sign. One thing in their favor is the retrofits: 1 Firepower, 1 Armor and 2 Universal, meaning you can get three firepower retros in there to really tune your gun how you want.
Chinese MBTs
Support Vehicles
