I just can't imagine liking both sexes. That'd be too hectic for me lol.
There are specific features of each sex that I like though, I don't really like 100% of both sexes... without going into too much pointless detail, I'd say that I generally prefer the personality and sexy parts of guys, and the figure, long hair, lack of body hair, and most other features of girls. That's why I like trans people... for me a combination is actually preferred. Not sure if that's the case with other bisexuals(or polysexuals, or w/e you want to call it. I don't really care about the label anymore. lol)