Sorry Viking, you didn't mention air superiority in the thread title or first post, so I assumed you wanted the best ground support plane because the Eastern Front was all about the ground unit success. As they did, so the country did. If you are just thinking of air superiority, I'd go with the Fw 190A model, probably an A-8. It wasn't a dog in any sense of the word. Later, when the D-9 became available, I'd transition right away. The Bf 109 was not up to fighting the Yak-3, Yak-9, and La-5 at under 15,000 feet, and the Fw 190 is the only other available choice, but the A, not the F, unless you wanted a ground support plane for that particular mission.
I really don't see any other real, live alternative unless we "what if" the Germans putting a French, Italian, or Japanese design into production. I also think that would take time the Germans wouldn't be willing to spend. Hence the Fw 190. As an outside possibility, they could have built IAR-80/-81's, but the Fw 190 would probably have been picked well before that option was even seriously considered.
Let's see, they had Messerschmitt, Heinkel, Junkers, Focke-Wulf, Blhom und Voss, Dornier, Arado, and a hand full of smaller firms. I wonder that Junkers, Arado, and Dornier weren't asked to design single-engine, single-seat fighters? Whatever the case, the Fw 190 would probably have been picked by the people in power at the time in Germany over an updated model from any of the Axis partners.