I guess I don't have much of a rhyme or reason to like the characters I do.
I don't like Mario. I play Mario because he's been my main forever and I can play him very well. But I don't like Mario the character. I don't like him as a character, if he even counts as one, and I don't like his games anymore.
I told this story a billion times in this site already, but I started playing Lucina as a parody or joke of sorts of my friend who was a Marth main. He was calm, intelligent and precise, while I was brash, aggressive, and fast. I also used her so I could make crappy "Waifu Marth", "Girl Marth" jokes. The jokes were on me, though, as I slowly started warming up to this character I had 0 background with. Before I noticed, she basically became a favourite of mine despite me not even having played Awakening, and all of my friends started started to criticize me for liking this character so much without even having played her game. Nowadays I finished Awakening and stuff so I guess all of those complaints were turned invalid.
And then there's Dark Pit. I like using him because he's easy, really versatile, and can kill in really fun and effective ways. Much like the other two I just listed.
So I guess that's my type of Smash character. Characters that are easy to play and have good ways of setting up for kills.