I have a degree in mechanical engineering and a career in computer science.
It’s really a matter of opinion and what you prefer. Mechanical engineering is very cool and you can learn a tremendous amount about everything (math, physics, chemistry, problem solving, electronics, programming, etc, etc) and you learn how to make things work in the real, tangible world. Everything you have ever seen or used that is man made (since mechanical engineers were a thing) has been touched at some point by a mechanical engineer. Academics is where my interest was, in the real world I found that many of the jobs available were maintaining assembly lines, designing random little parts, or analysis on an existing system/machine/process/etc. These jobs also include lots of overtime, stressed deadlines (automotive especially), living in a small town (manufacturing especially), and surrounded by older generations as co-workers.
Computer science on the other hand is less fun to learn in school as most of it is tedious and you never really do anything in the tangible world. However, the real world work is the same type of mental problem solving challenges that I enjoyed so much about mechanical engineering in school. The workplace is generally much more fun, laid back, and younger (think Googlesque work environments).