The Stugs were very suitable to be posted in an AT role in a keyhole line of sight zone. Stugs were widely used in this role because they were available in large numbers. The Germans produced better tank destroyers, but in smaller numbers. The Marders and Jagerpanzers had similar cannon, (long 75mm) but better aiming systems. Later the Germans made some really powerful tank destroyers like the Elephant, Nashorn, and Jagdtiger with the 88, but they didn't have the numbers to check the red tide.

The Stugs were produced in large numbers. Essentially it is a PzKpf-IV with the barrel protruding from the front hull instead of a turret. The Germans had industrial problems (probably related to allied bombing) they were producing PzKpf-IV chassis much faster than the turrets.

The Stug B and Stug E had short barrel 75mm cannon not suitable for armor piercing at long range. The Stug F and Stug G had long barrel 75mm, which were deadly at long range. There were also several models of outrageously large caliber Stugs like the Stug 33B with a 15cm gun, intended solely for putting high explosive into fortifications. The Stugs began to appear in 1940 and became very common in '42 and '43 (probably related to the industrial problems producing turrets). They remained in production throughout the war because the PzKpf-IV chassis was very reliable. The Germans had lots of problems with breakdowns in its heavier AFVs.

You are exactly right about the M-10 Wolverines supporting Shermans, that was their primary role. I also like the Hellcat, which is almost like the Wolverine but with minimal hull armor so its much faster. Both of these vehicles were vulnerable to artillery bombardment, and infantry inside of grenade range. Usually they were backup support, when a Panther or something was discovered the tank destroyers were called up. A wise commander did not expose them until absolutely necessary. Let the Shermans do the dangerous duty.

I'm a big fan of certain light tanks especially ones with a 20mm autocannon. The PzKpf-II was so armed as well as the T-30 and T-60 Russian tanks. These guys could not pierce the hulls of heavy tanks, but they could tear up everything else in a hurry.

After Kursk the Red army reported that rate of fire and rate of traverse were the extremely important features in a target rich environment. The KV-2 with it's monstrous turret and cannon performed poorly at Kursk.