The Panzer IV is pretty good for its tier, especially with the 75mm L/70 gun. Unfortunately, you have to use that hideous Darth Vader turret to fit said gun (or the 105 derp gun from the Hetzer), but it is very much worth it. It ends up making the tank an excellent sniper.

Also, I just got my E75 fully upgraded, aside from the top engine...that thing is a beast, lol. I was in one of those "hold back the tide" situations where I was the only person on my team who went down a particular path...opposing me were an IS-4, a pair of Tiger II's, a Jagdpanther, an M6, and a VK3006DB. They seemed to think there was something behind me, because they would not just rush/flank me. That said...I think I bounced about 60-70 shots from the lot of them before they finally managed to kill me.

Meanwhile, the rest of my team did the lemmings thing and steamrolled everything on the other side of the map, lol.
Oh, and by the by...I have noticed something interesting with the E75: shells that bounce off your tank have a chance to hit other parts of your tank, depending on their trajectory. For example, I had a spotless tank in a match earlier, and the very last person alive on the other team managed to get a shot off; that one shot left a bounce mark on the upper glacis plate, AND a secondary bounce mark on the front of the turret. So, just something to watch for, if you have strong chassis armor but weak turret armor. Not sure why I never noticed this before, lol.