I ussualy buy 'unique' ones who completly change game of style like osttruppens, luftwaffe, close air support ( you can't buy it, but war spoil drop) and so on....
Very simple. Get 3-4 rifles. And than decide. If osteer you can freely go leutnant if okw go captain to instantly prepare for puma or even p2. Than decide use m1919 and get jackson spam or get captain > stuart > jackson spam or get 3 rifles at the start + assault engy and get captain + stuart > leutnant or wait for m10's and sherman buildozers
One strat I've had *some* success with is rushing their base with your tanks. As long as you can get the KT and Elephant some distance away, heavy tanks will take forever to turn around and get back so you should be able to get a few buildings before retreating again.
I think a lot of times I get so focused on destroying the heavy armor that I miss other easy opportunities like a base rush.
What is the point of destroying okw base ? They will for sure have all tiers in the middle of the map.And you can't do base rush on maps like rails and metal.
AT guns. Use the "take aim" ability at vet1 to gain 70 range. With "premium" rounds and vet they can easily take on even the heaviest vehicles. Don't underestimate them!
Jacksons are also very good, but must be kept outside of the Jagdtigers/Elephants range.
There are not much more options besides that. Rear echelon blob with lots of bazookas can somewhat work against medium tanks but it is nothing i would recommend against the Tiger 2.
The smoke grenade from riflemen can slow vehicles down, if hit directly - keep that in mind.
Smoke nade has same effect as at nade (just for limited time right) ?
At guns honestly can get taken down by stuka zu fus.