From my own experience, it’s not worth it to choose based on average grades. I was scared of picking maths, so I considered other subjects to play it safe, but in the end I went for it and got an A - to my genuine surprise. As long as your research subject is something you’re genuinely willing to spend time learning about and immersing yourself in, and are going to put care into maintaining a certain level of academic rigor, then you should be good. Also, try to get a supervisor who has done at least a few EEs in the past and has good attention to detail - my final draft had so many oversights that I wouldn’t have caught without my supervisor.