abelpc_uff

I was offered two opportunities for doing a PhD in Computer Science: one in the USA (Texas Tech University - http://discl.cs.ttu.edu) and the other one in Sweden (Umea University - www.cloudresearch.org). TTU is not that famous but the Professor is very good and the research he conducts (Big Data). Besides that, I was offered to work at some well known national labs like Argonne and Oak Ridge. In Sweden, I was offered a RA position and they are one of the leading groups in Cloud Computing Research. From Microsoft Research (http://academic.research.microsoft.com/) I could notice that the researchers at Sweden are more world wide famous. My question concerns about learning how to do research and opportunities during/after the PhD. What would best suits my situation, where I need to learn to work independently? I would like to ask about the Swedish structure of a PhD compared to American one. As I do not have a master's degree, I do not know if I would be ready for the Swedish structure (independence first). I have talked to my prospective advisor in Sweden and he told me I am able to pursue that, but from your point of view, what do you think of a candidate without a Master's degree? What could be my worst difficulties to overcome since I am not experienced in the field? I am asking these questions because the educational systems in both countries are different. While in the USA we take more classes before doing research, in Sweden we start doing research right away (under the guidance of the supervisors, of course). I want to work as a researcher in the future, may it be on industry or in the academia. What else should I consider that I did not touch in this question? Thank you all for your help!