Let us assume an early POD, preferably before 1700. Let us assume that Prussia is less successful in conquering more land. For instance it does not win Silesia or valuable areas in western Germany. And Saxony is stronger, thus being a counterforce to Prussia. In other words, The Habsburgs remain clearly much more dominant than any other German state.
Alright, then in this case, 19c Germany has a bunch of independent states with strong industrial sectors: Saxony, Brandenburg, probably more than one state in the Rhineland. This would encourage more balanced federalism, as opposed to Brandenburger ("Prussian") domination. There might still be a Kleindeutschland if those midsize powers wanted to avoid dealing with the Habsburgs, even... Or alternatively the Frankfurt Parliament, having no equivalent of Prussia to deal with and only Austria, would succeed, which again implies there might well still be a Kleindeutschland.
So the domination in this ATL would be less by Austria and more by western Germany. In the west, unlike in Brandenburg, there was no Junker class, and the peasants had more rights; a Frankfurt-based government would be a lot more liberal than a Berlin-based one. Eastern Germany would be like the American South today: poorer and more rural, and full of resentment at domination by the western elites; race relations might well mirror American ones as well, with Poles taking the place of blacks, escaping eastern persecutions to the Rhineland only to find that none of the enlightened universal-vote types there actually wants to live next to a Pole.
Trying to figure out a Grossdeutschland in this scenario is a bit weird. For the record,
my TL does have a Grossdeutschland, dominated by no one, coming from a very different ending of the *30 Years' War; it maintains a capital in Frankfurt, has the same east-west racial politics mentioned above, and has an uneasy situation with the Czech, Slovak, and Hungarian minorities, at the end of which they declare independence in 1999. But this assumes a weakened Austria.
With a strong Austria... you'd have the classical liberals in the west feeling neglected by Austrian domination, a weird situation involving Prague and probably Germanization of Slovaks and Hungarians, and a still-resentful east-of-Elbe German population full of Protestant nationalism. Czechs would probably be like the Rhinelanders - industrialized, resentful of paying more taxes than they get in services, and for geographic reasons more federalist than secessionist. They'd have the economic power to demand to be their own state within a federal Germany, rather than part of Austria.