With the category definition expanding as it has, I feel that War Thunder is basically the MMO for WWII action. While you don't have a character and there is no persistent world (yet), the game still manages to scratch that itch for immersion that WoT never really addresses. There is a good sized learning curve, and some unforgiving mechanics, but I feel that these things actually give the game some meat so that when you get good at it the resulting revelation is worth it.
The tanks in WT can be towed and righted by allies via use of an animated tow cable. There are animated human figures in the vehicles so when you are operating an open topped SPG you actually see the crew. The terrain is interactive, to include craters from your bombs and rocks that roll away from the front of the vehicle when you hit them.
Also, I feel that the damage models are much more realistic in WT, and lower tanks can be competitive against higher tanks with a good hit or by calling in artillery (which most vehicles can do once you have the vehicle upgraded enough). If your tank has multiple guns like a Lee, you can actually use both guns as well as the machine guns.
Be prepared to do a lot of keybinding and dialing in of your controls, but after that you will feel the beauty of the complex interface that gives you choices and responsibilities in manning your vehicle.
With the World War mode I hope that Infantry, armored cars, and towed pieces will be available to play, but even if that doesn't happen the game is already fantastic. Driving a half-track with a 75mm gun around and sniping at tanks was a blast. Thank you Gaijin for giving me the choice to play a vehicle that is not a tank, but was a classic presence on the battlefield.
MMORPG players are often like Hobbits: They don't like Adventures