What do you want in a significant other? Well, there are two ways to go by answering this question:
The immature way- This is especially for guys. You can state all of the shallow reasons, mostly physical attributes. And it's okay to be immature-we all are! Try to say with a straight face that you do not laugh when you fart. We are all immature to some degree.
But, it's more important that you also take a serious approach. It's just as much what you need as what you want. Maybe it's someone you can tell everything and know you won't be judged, or someone who you can hug and hold in your arms after a rough day, week, etc.
What I need, first and foremost, is someone I can tell anything to and not worry if they'll think less of me. I am not in the very least an open book, and not even a handful of people know me inside. I can only really talk to one person.
I need someone who I can have a true, deep conversation with, someone who can challenge me mentally. I only know a few girls that can truly challenge me on an intellectual level, and I could never be with someone who the deepest they ever 'think' is, "I bet it would be cool to be an astronaut (or scientist, etc.)!" I'm 17 now, and I need some sort of mental stimulation to stay interested.
As you can tell by my screen name, I love to laugh, make jokes. I would need someone who understands my humor. I have a strange sense of humor- a blend of strangeness, and I am always quoting things- and I need someone who laughs because they get the joke, not because I'm laughing. I also need someone who can make me laugh at any time.
Also, things haven't always been easy-going for me, and I would want someone who could make me smile no matter what- especially if I don't want to.