These are my opinions:
S Tier
SU-85M - This tank is simply a beast with 75mm of sloped armor at 52 degrees. If you do some hull wiggling, you can bully Tigers and Panthers. At 5.0, it’s at a perfect BR because you mostly fight 4.7-5.3 tanks. If you do face 5.7+ tanks, there usually aren’t too many. It’s fast, the gun is decent, but it suffers from your usual casemate tank issues. You just have to watch your sides, don’t expose your driver’s hatch, or commander’s cupola side.
T-34 STZ - At 4.3, this is the most heavily armored USSR T-34 tank. The hull is equipped with 15mm of additional applique armor, which makes it harder to pen when angled. The turret is also smaller than the T-34 1942, with smaller cheeks and a less prominent turret ring, which makes the turret a bit troll to penetrate. The hull sides are less protected than the T-34 1942 and E, but most tanks can just shoot right through their side protection anyway. It’s also one of the fastest T-34s in-game. Its reload time is also slightly slower than the T-34 1942.
T-34-85 and T-34-85 (E) - I’m grouping these 5.7 tanks together because they’re exactly the same, except one’s a premium with bed spring armor. Coming from the T-34-85 (D-5T), this tank is a major improvement in a lot of categories. It has a 3-man turret instead of 2, faster reload, thicker turret armor, and a somewhat useful APCR round. It’s the pinnacle of the T-34 tanks in terms of firepower and mobility, but its armor is very deficient at its BR, unlike the T-34s at 4.0. You can’t brawl it out with most heavies directly and need to rely on flanking with its speed. Overall, the 5.7 Soviet lineup is pretty good though.
A Tier
T-34-100 - A T-34-85 uparmed with a 100m gun that can point and click most threats you face from 5.3-7.3. Incredibly strong in down tiers because you can UFP Jumbos and Panthers, but can also fight back in uptiers. Gun depression is terrible so fighting on uneven terrain can cause issues. AFAIK, this is the only T-34 that comes with smoke grenades as well.
T-34-85 (D-5T) - This is the first T-34 you unlock with the 85mm gun, which is a big improvement over the 57mm and 76mm gun. It has good penetration, and its post-pen is usually lethal.
T-34 1942 - This tank is functionally the same as the 1941 model with a thicker turret, more variety of ammunition, slightly faster reload, and the driver’s hatch is upgraded with a layer of Stalinium. Overall, not too many major improvements on this tank like the STZ and E.
SU-122 - At 2.7, this tank is a low-tier beast and can derp literally every tank at its BR. With 45mm of sloped armor, you’re basically frontally immune to most calibers at that BR. However, the main drawbacks with this tank are its low-velocity gun, very long reload time, and the gun is basically worthless if you’re uptiered against 3.7 tanks.
SU-100 - The SU-85M’s big brother armed with a 100mm gun. The 100mm gun boasts 239mm of armor penetration with a much faster reload speed than your usual 122mm tanks. Panthers, Tigers, and Jumbos become easy prey for this, but you’ll struggle against 6.7+ tanks if you’re in an uptier. The main drawback is you have the same armor thickness as the SU-85M, but you can still wiggle bully.
B Tier
T-34 1940 - At 3.3, this is the first T-34 you unlock, and for its BR, it’s very well protected against tanks equal or lower to its BR. The main issue is the L-11 gun struggles to penetrate a lot of tanks frontally like the M4A2, M4A3 (105), other T-34s, KV-1s, etc. I’d rank this tank A-tier, but the main drawback is at 3.3 there’s no other Soviet tanks that fit the lineup. This tank is more or less just a jumping-off point to the better T-34s waiting just ahead. It can club very hard in downtiers though.
T-34-57 (both versions) - I’m grouping the premium one in here since they’re basically the same tank. I’m ranking this B Tier because while the 57mm gun has amazing armor pen, it has very little explosive filler and post-pen damage, so it’s pretty rare that you just flat out one-shot people. It takes on average 2-3 shots to kill most tanks. Armor protection-wise, you’re basically the T-34 1942, but at BR 4.7 facing off against tanks that have guns that well overmatch your armor. To me, this tank is a bit overkill simply because the F-34 gun is more than a match for most tanks you face at its BR range on the 4.0 T-34
T-34 E - As a premium vehicle this is the most unique looking T-34 tank ingame. It has bolted on 16mm applique armor on the turret and sides giving you a modest protection increase. The turret is also one of the smallest out of the T-34s ingame and the applique armor obstructs the turret cheeks that most tankers aim for. At 30.6 tons this is the heaviest and slowest T-34 currently ingame. Overall it’s a fairly well rounded tank that fits into a 4.0 line-up.
SU-122P - It’s the SU-85M equipped with the same gun as the IS-2 at 5.7. It has similar performance to the SU-100, but with a nearly double the reload time, and more explosive filler. This tank derps everything in one hit, but for a premium it’s also competing against the KV-122 which has the same gun, and reload time. Having driven both, I’d personal recommend the KV-122 over it simply because you get a turret with the same exact gun.
C Tier
SU-85 - The regular SU-85 at 4.3 has a beasty gun for its BR, but unlike the SU-85M it has non-existent frontal armor for its BR. So unlike the SU-85M you can’t bully tanks and have to play more like you’re an unarmored TD ambushing targets. Also, the 85mm gun is a bit overmatch for 4.3 because the 4.0 T-34s can pen just about everything frontally unlike the 5.0 SU-85M which often runs up against Tigers, Panthers, etc.
