- The Cromwell british tank: Would be the fastest true tank I think at around 40 mph? Would split the speed difference between the M18 and the fastest current tanks by slotting right into the middle of the 30-50 mph gap. It would not unbalance anything in my opinion as it has relatively weak armor and gun (would be comparable to the Panzer MkIV, basic Sherman, and T-34/76 overall probably). What would it add that we do not currently have? Two things, a fast tank, and a true British tank, which we currently do not have. Due to speed, perhaps it would be lightly perked, maybe 1-2 perks?
- The IS-2/JS-2 Soviet tank: This would have the most powerful gun in AH, and as such, I'm sure this tank would be perked probably similarly to the King Tiger as a result. Offsetting the extremely powerful gun however would be the very slow reload time (1-1.5 rounds per minute according to some sources), and the fact that the armor and mobility weren't really all that great relatively speaking. What would it add that we don't have? A historical counterpart that could challenge the King Tiger (M26 Pershing could fill this role also, but was introduced so late in the war that perhaps the JS-2 would be better). Also an extremely powerful gun for taking down towns and hangars. For GV vs GV combat it would be very formidable, but handicapped by its slow rate of fire, so not dominant.
- The M-36 Tank Destroyer: This would be the second most powerful gun if the JS-2 was implemented, and most powerful compared to existing vehicles. However it is not fast like the M-18, and is weakly armored and vulnerable from the air just like the M-18. Would be perked no doubt probably something like the Panther or Jagdpanther. What would it add? A better gun than anything currently available.
- For something very different than anything we currently have, how about the M-7 Priest: Very powerful 105mm howitzer. Could use indirect fire on towns/bases, but could also use direct fire against other vehicles. What does it add that we don't already have? Artillery! Other than naval guns, and some limited degree of fixed manned guns on bases, we really do not have artillery at all. For more realistic and interesting ground combat we need true combined arms, and this would add artillery to the armor we have. Infantry is a topic for another post...