I think only you can know the answer--and my writing what you have, above, you're already well on the way to your answer. I feel strongly that it is an absolute MUST to commit to the program that is the best "fit" all around...not the biggest name, but the program that will give you the most support so that you achieve what is most important--reaching your career goals. That is absolutely the pivotal end goal, and no particular university's "name" is going to help you in your career if you can't finish or succeed at what you started. Best of luck to you; it sounds like you have some really exciting decisions to make! Go with what your gut is telling you...maybe that's hard for a scientist.