My favorite to watch and my favorite to play are probably very similar haha. I have never played a horror game (unless you count The Walking Dead) so idk if I like playing them or not, but I definitely like watching people play them.
I also really enjoy playing and watching story-based games. Not sure what the genre is called, but games like The Walking Dead, Life is Strange, and Uncharted 4 (I haven't played that one, but I love watching it!)