I need a bit of advice. I am currently in my third year of a math PhD program.
I have been working with Prof. X for about 2.5 years now. He thinks he is my advisor but I have also been working with Prof. Z who is my chosen advisor for many reasons. In short, Prof. Z a much better advisor for me (nicer to me, better at helping me learn, more available, supportive for me to attend summer research programs, etc.) and I want to work in the research area of Z and not X. I know that I will be successful with Prof Z.
Last semester I was traveling most of the time doing research related to Prof. X's work. In that time, I solidified that X's area is not the area I want to study. I am trying to finish a paper with Prof. X though.
I need to tell Prof. X that I want to finish the paper but then work with only Prof. Z.
I am thinking that telling Prof. X in person is best; however, I am also worried that Prof. X will have a bad reaction (due to his personality). Maybe it is better for me to tell X over email so that the initial reaction doesn't happen with me there.
Any advice would be really helpful on how I should tell him.
Update: Hey all. Just as an update. I told him today. I thought he would be mad but it was more of a sad reaction. I felt bad, but I know I’m making the right choice. Thank you all for your time and help with this :)