I played Austria for 70 years and its the most fun ive had in EU5 1.1

Austria starts surrounded by threats on their borders. Hungary is in the east and Bohemia in the north. Both start with larger armies than Austria so initial diplomacy is critical to deter invasion. They start anchored on the Danube and they need to increase their influence up and downstream. Expanding into Bavaria and Hungary are natural ways to build a strong nation.