WoT is not at all what I would like to see HTC become. I find WoT to be as gamey as can be with eye-candy and "power-ups" being the main goal.
I think the tank combat in HTC is more "realistic". With that said, the big area that could be improved upon is not so much the tanks themselves but the environment in which the tanks do combat in. First, the terrain is too smooth. There is no mud. There is no sand. No fog (or rather very little near ports, but in general there is none). There are too many constant variables that should not be, imo. However, just how deep can the coding be taken and just how much work it will take to add in anomalies that add environmental/immersion changes only HTC really knows.