Hi I am an undergraduate student of physics in the university of Athens. I am reaching my final year of studying and we are asked to select and work with one of our professors so that we can make a (barchelors) thesis about a specific specialization. I have know for a long time that I want to be a theoretical physiscist so my options were narrowed to two. The first professor is speciliazed in Phenomenology and he told that if I choose him we will work with the standard model and in general with quantum field theories. The second professor is a more therotical physicist and he offered me a thesis on Q.E.D. My question is what field of studying will help me more ?