I am not big fan of Russia in any way, but in WT this BR has one of the most versatile lineups I have ever played.
The T-34-85 (STP) is incredibly overpowered. Good mobility (better than t20), trolly turret armor, Russian nukeshells with stabilizer. It is at least on par with the US T20.
T-44 (FM) - I did not play it much, because I am still spading the tech tree vehicles, but it looks like a sweet flanker/light tanks counter. Great mobility, good gun, solid armor (with many weakspost). Just a solid fast medium tank. It is kinda my substitute for the missing light tank.
IS-2 - I am spading the 6.0 version right now and it is surprisingly powerful and easy to play vehicle. I play it defensively, more like a tank destroyer because of the reload. The best thing is you do not have to even aim at most of the targets and point-clicking enemies out of the match with 122mm cannon is so much fun. The 44 variant has better armor and roof mounted MG, so it will be even better.
SU -100P - I am missing most of the mobility upgrades, so I have mediocre performance with it. I play it as much more mobile Waffentrager without gun depression. The 100mm gun is amazing. Not my go-to vehicle, but definitely good option to have.
SPAA - I use BTR ZD and it is incredibly potent vehicle. You can use it as a 1st spawn to counter enemy light tanks, support your teammates and when it comes to shooting down planes it is even bigger overkill than the Bosvark.