Today, German ships are not named after generals, admirals, politicians or other persons. They are named after states, cities, rivers or other geographical features. There are only very few exceptions:
Gorch Fock, named after the pseudonym of a author and these is currently the oldest ship still in service (i.e. from a time with different naming rules)
Knurrhahn, named after a fish species
Planet, named after a astronomical body (actually name is used often for naval research ships)
I think that there are very good reasons NOT to name ships after people, battles, political symbols etc. It is very likely that these names are not acceptable for future generations - as the names Scharnhorst, Gneisenau, Blücher, Scheer, Tirpitz and Graf Spee are today not longer acceptable in Germany. E.g. parts of Kiel harbor are re-named, so that not longer people like Tirpitz and Scheer are honoured. Bases and parts of bases are still named after people and in the last years are lot of them were re-named to remove the names of fascists and other enemies of democracy.