TUHH or U of Stuttgart?

You cannot say one is "better" than the other - they are different, but it entirely depends on your preferences, needs and expectation which one you like more.

Could you please elaborate a little more on what the advantages and disadvantages of both might be?
I understand that since Stuttgart is a part of the TU9, it would be good for someone interested in pursuing a career in research. But TUHH is neither a part of TU9, nor is it a university of applied sciences. So what kind of job would one expect after graduating from there?
I've read that Stuttgart is a dynamic region when it comes to research in the sectors of automotive engg, infotech etc. but does the same apply to research in environmental engineering? And what about the same in Hamburg?
I've also heard that (just a generic statement, I could be wrong) at some universities where professors focus greatly on research, their focus on teaching is less. Would that be true for either of these universities?
As of now, I believe that after my masters I would want to work at a research institute or university before doing a phd. But I would want to do a course which would be flexible and allow me to say, take up a job in the industry in case I change my mind during the course of my masters studies.