What do you like about mechanical engineering and/or electrical engineering?

I assume you mean "interesting". That's of course a subjective issue. From my own point of view, I'd say most definitely yes. Trying to be objective, I'd have to say that pretty much everything in the world is governed by the same principles -- in particular, natural and biological systems. In order to solve a problem in theory, you may be able to limit your concerns to ignore mechanical and electronic principles. But I'd say that's pretty unlikely. In general, if you want to build any solution to any problem that involves having an effect on the real, physical world, you'll usually need mechanical or electronic devices, and in today's world, most likely both. So are these interesting? Everything I've ever built has used one or both of these, so in my own biased opinion, absolutely.

If I'm interpreting this question correctly, you're asking if both of these fields are interesting. I'd say that they're not only both interesting, but you'll find that they both pop up in solutions to many of the same problems. The reason is that very few mechanical systems of any complexity these days do not have electronics in them, and usually some form of computer processing elements. If you study either of these, I strongly suggest you branch out into some contact with the other. I would also say that if you dabble at all in electronic engineering, you'll be hard-pressed to avoid computer engineering, not just the use of computers. In my studies of both undergrad and graduate engineering, I was always being confronted with situations that drew on both areas. You also would find that a bit of chemical and bio-engineering would be interesting, entertaining and very useful in explaining a lot of phenomena that you'll encounter in engineering.

I did my undergrad in Mechanical engineering, hence I can speak a bit on that. Mechanical engineering is considered as the mother branch of engineering. It has various disciplines such as Design, Manufacturing, and Thermal. The thing I like about mechanical engineering was that you would first start with introductory courses on all these various disciplines and if you decide to like one, you can further advance your knowledge by taking more advanced courses. Even when it comes to a job, you can pick and choose based on your interest in these disciplines.

One thing I would say was how fantastically mechanical engineering has adopted computer technology over the past few decades, which brought a revolution in this field. So even if you are interested in pursuing mechanical engineering, be sure to have a good working knowledge of Computer Science as you will be able to make wonders.

Partap, what I like about mechanical engineering is that there is always something new to learn about or a new creative way to solve a problem. I have moved between consumer electronic and medical devices. As an young engineer, I learned about the product development process and working with the factories to make my designs reliably in mass production. Later, I was given challenges that I applied engineering principles and concepts to resolve thermal issues using radiation heat transfer and free convection. In medical, I worked with PhDs to solve issues in tissue optics. Yes, tissue optics is a real thing.

After a while, I was looking for new challenges and incorporated people management into my skill set with positions that included project management and eventually people management.

The main thing is that I have continued to learn and grow throughout my career, always using critical thinking.