Have a look at Ivona.. I just compared several of the sentences in one of those repo files from the google 16k, to the German man/women on the Ivona TTS, and the Ivona one sounds a LOT better.
I had an eye on Ivona already. The problem is it's not as free as Google or Bing TTS. There is only a 60 days trial and the actual pricing after the beta period is also unclear.
At least the german voice from Google is IMHO as good as the voice from Ivona (in fact it's even more applicable as it sounds more formal while the Ivona female voice might have a slightly Berlin accent or so).
Let's see and keep an eye on what happens with Invona (also now that Amazon has acquired it).