You should buy a 2nd Tanker and run 1 Tanker with T28 that has HE ammo and the 2nd Medium you can go for T34 76 for mobility or T34 85 for firepower.
The T28 costs 100 cr per spawn and is an infantry butcher if you play it in defense and with a good team. This is why 99% of the community hate the thing, cause they play it alone and in staged, vs Panthers etc. Dont play the T28 in staged, ever. Play it in war, strategically, in single line assaults with wide open areas and some friends on Discord. Trust me, it works.