The only country in Europe (escluding Muscovy which I consider ROTW) I find fun is Austria. But not as the usual path towards the HRE vassal swarm, but instead forming Germany by using your position as emperor to grow in strength and sabotage the HRE from within. I flip protestant early, and then blitz-CB the emperor once the leagues fire to stomp them in a minimalist league war (well, except for me). At that point I should rather quickly become emperor again, then once I am the last elector remaining I throw the emperorship to a random OPM and wardecc them to dissolve the empire.
Other than that though I find the new European content rather disappointing. No reason to play the German minors because Austria is OP, Castile got screwed over by the changes to the BI, Aragon got nerfed, the French vassal swarm does not work properly, Swiss earlygame is broken (and they start horribly boxed in), the new mission trees are bad.