AT guns have depression about 2°, and you can’t place it on angled ground. How I supposed to aim down? Because of this it’s useless in most of situations where you can use AT gun for your advantage.
Also in Lone Fighters you have to aim by this huge circle.
I’m hoping that once we will able to MOVE At guns that we will be able to get them down slopes a bit to obtain desired angles, if we’re not able to build them anywhere but flat terrain.
For soviets it could be the 76mm 1931 or 1938 model on Moscow, and definitely 85mm M1939 for Berlin.
1931/1938 were similar and 1931 was the most common at the start, 85mm ended up the most used by the war end.
For UK it would be the QF 3.7 inch gun (94mm), I’m not informed on how common they were in North Africa
Italy could get the Cannone 90/53, but I recon the German Flak 8.8 is more famous on North Africa, so maybe the Cannone didn’t saw much action, I’m not informed about it.
For USA, they developed the 90mm M1 AAA in 1938-1940, but until May 1943 they didn’t start producing the M2 model capable of lower depression needed to target tanks.