Interesting article regarding the abilities and vulnerabilities of the Russian tanks:
Armor: Building A Better Defective Tank (strategypage.com)
While the official most modern Russian tank is the T-90M, it is not the tank Russian crews prefer. The favorite is the T-72B3, which is as effective as the T-90 and lacks a lot of the additional features on the T-90 that don’t work, complicate operation of the tanks and the crews must maintain. The T-90 is for export customers and no Russian troops use the T-90 in peacetime.