I'm honestly not sure. My personality is literally messed up so it was difficult for me to assess which houses I leaned more toward. I consider myself a very kind and loyal person, but that's only to the people I like. I can be downright vicious, crude, and unbearable if I don't happen to like you and I won't put up a facade just to make peace. I consider myself intelligent, but Ravenclaw and Slytherin exemplify two different types of intelligence.
Ravenclaw praises booksmarts and more academic oriented intelligence, whereas Slytherin exemplifies cunning, resourcefulness, and cleverness. I am academically intelligent, but only certain areas. I can easily whip out A's in advanced college level history and English classes, but I'll struggle to get C's in basic math classes. >_>; I consider myself more resourceful and quick thinking, able to come up with practical solutions, etc. Despite my generally kind nature, online and irl I do feel as if I have a darker side to my personality that I actively try to suppress. I can be brave, and do brave things, but usually only for myself. Being brave for another person is increasingly less likely for me to do.
In conclusion, I'd say probably Slytherin. I have traits that belong to all 4 houses, but Slytherin seems to be dominant. Not to mention, since we talking in theory here, if I were a student at Hogwarts I unashamedly admit I would seek to be the best damned wizard there ever was. I'd be extremely ambitious. I mean come, this is freaking magic we're talking about. Being in a school like, the quest and desire for knowledge would literally consume me. I'd never stop trying to be the best. However since the sorting hat takes request into account, I'd probably ask for Gryphondor like Harry Potter did. Honestly, who wants to be in a house full of little self serving pricks? It sounds like a nightmare.
Edit:
Simply because hufflepuff is the reject house, that would technically make it the superior house, as it accepts and teaches more students making it more competitive. Cedric diggory was said to be an amazing wizard. Accepting rejects =/= poor skill. You'd recieve the same magical education all the other houses would. In theory.
Edit:
I just took the test lol, because I was curious.
Hufflepuff
68%
Ravenclaw
62%
Gryffindor
55%
Slytherin
52%
So I got sorted to Hufflepuff, but you can see it's pretty evenly distributed.