I would straightly prefer Germany.
1. US is very expensive, Germany is not.
2. Considering , you will be joining course which is taught in English, Learning additional Language , which is very beneficial for your career now or later. English is not only the language to be learned. The more languages you learn , the more exposure to global system you learn, whichever the industry you work. Believe me, I am learning French now after i came to Belgium. Languages learning is beautiful. You , not only learn a new language, but also you learn people, culture, history, their amazing aspects as well. Till my High School , what all i was exposed to is only, Tamil.
Then in my engineering, i learned English with difficulties
Then, while working at Mumbai, Hindi came along
Then now i am glad learning an another nice language French.
Per my view and opinion, It is good to know more languages than what your normal surroundings and environment teaches you.
3. When going for Doctorate, generally in Europe, you get more stipend than in US. And less living cost in Germany when you do that. So you save a lot in higher studies or in Post-Doc.
4. Since you learn German language, you have access to most of the European countries where German are spoken. Remember, you can expect one in Europe speak 2 or more languages easily.
5. As what i hear from some of my friends, US has a culture where (some, may be) the thesis of your project requires concerned specific approval of Professor/Industrial partner to proceed. They have more influence in the paper outcome and the research direction you want to proceed. I hear from my friends here that, in Europe you have more freedom to choose the project you wish to and make your opinions and suggestions.
6. There is a work and studies balance you can expect in Germany. I am unaware about US. But the feel and sense of Insecurity exists in US while studying due to finding the jobs and getting one,retaining one after education. In case of Germany as well, it exists, But Not so violently.
7. By studying in Germany, You have access to the whole Europe best places, Univs, Cultural events etc. You can travel at very simple cost from one best place to another best one within Europe. Connectivity is too good.
8. You get to know the best professional culture in Germany. Perfection. Made in Germany Tag. Peoples loveliness to know more about you (They love to know about the people from other cultures). If you are skilled enough to contribute to Germany labor shortage, you are welcome. Their political weapons don't have Immigration policies as one. Friendly one.
9. People are much more friendly and with the thought of willingness to help you. You can befriend one easily with smile and talk in a bar.
10. You are less likely to get fired , when you are in Germany. Social system takes care of you when you contribute , and when you are in Job. I am not aware in US.
11. You learn a lot about different cultures. You will not have time to learn things which you wish. You actually go busy due to the different people and cultures come along.
12. You will learn lot about Cars
13. You have access to some of the beautiful Christmas Markets in the world
* I never lived and studied in US. All are my own views and understanding from my friends there, news , experience. So you cant take all my opinions straight away to decide. If there are things to correct, i will certainly do.!
Wish you good luck!