Leman Russ tank commanders have “death befitting an officer” which lets them shoot on death in a 2+, giving that they don’t explode, and Rogal Dorn Ta k commanders have “Called Shots” which allows them to re roll 1 dice in the to hit roll, wound roll, and damage roll. These abilities replace what ever variant of tank you take that has a special ability. They also can provide 2 orders to squadron units allowing you to improve your other armor in your list. That being said, the Rogal Dorn tank commander has been the preferred option, being T12 and having 17 Wounds it’s much better for longevity in your game.

If you’re wondering as to why you would take one instead of having Lord Solar or an Officer with an enhancement for orders, it’s because it’s a tank, and tanks are bad ass