The 2 reasons I love coding:

1. Making stuff. Maybe obvious, but there are very few other fields where you create stuff so freely and easily. And it's not just about being creative, it's also adding value in the stuff you make.

2. Problem solving. The same reason puzzles and riddles are fun. There's something satisfying about wrestling with a problem for some time and creating a correct solution.

As a result I don't really have a favourite field, as long as I can do the above points, I'm happy.