I have no preference–left side, right, head at foot, perpendicular. Mostly I go for being near a window for coolness.
The first apartment we were in, I slept on the side closest the alarm clock. Our headboard is about 8 inches wide, so the clock is in the middle now where we can both reach it, but the side we sleep on has stuck through several moves.
I’ve occasionally got into bed on her side, forcing her to sleep on my side, but she doesn’t like that.
I’m right-handed, and in our present place I sleep on the right side. But in the last place, I slept on the left side. That’s because I sleep on the side that is not against the wall. (Have to keep the wife from escaping.)
Crap, I answered wrong, and answered stage right rather than while facing the bed.
FWIW, I sleep on the LEFT side in that scenario, and am right-handed. It doesn’t matter to me which side I sleep on, though I do tend to prefer sleeping on MY right side. But I can do that anyplace. It’s just how it shook out, and since we each have our own night-table with stuff on it, it makes sense to keep going that way. When we move, I’ll ask him if he cares which side he’s on. 
I’m right-handed, and prefer the left side – but so does my wife. I LOSE.
So, I usually end up with my ass pointed at her, and my face is peering over the side of the bed.
When I was sleeping solo, I’d tend to actually sleep diagonally – head near one corner, feet toward the opposite corner. I still want to do this, so every now and then, my wife will kick my feet away.
I LOSE.
I think it’s time to go for the king-size.
I’m right handed, but I sleep on the side of the bed nearest the door and/or nearest the phone. This is because I’m a light sleeper, and would wake up if one of the kids was making noise. My wife can sleep through a ringing phone, so I need to sleep on the side nearest the phone. When we’re travelling (hotels, staying with relatives, whatever) we stick to that arrangement. It happens to be the left side of the bed in our house.
Yes, he LOSES. Good day, Sir. I said, GOOD DAY!. Always happy to see another diagonal sleeper. Women hate that shit, but the men folk understand!
I sleep on whatever side is closest to the bathroom, since I have to get up at least once a night. Right now, that is the right side. (Right handed female)
Leftie here, and I sleep on the left side of the bed when I sleep with my wife at all. She steals covers and pillows in her sleep and falsely accuses me of the same, so sleeping separately is more restful for both of us. Also, our sleep schedules are different.
But where are you with respect to the closet, because that’s where the monsters live, you know?
I (male) sleep on the right side, which is furthest from the door and nearest the bathroom, which doesn’t make any sense. I have no recollection of how I got the right side. We do swap in hotels to put my wife nearest the bathroom.
Every time I’ve shared a bed, it’s been on the left side. Realistically, though, it’s that I prefer the side that’s the perfect combination of being farther from the door, and closer to the wall. That seems to usually be the left side. I’m an odd duck when it comes to where I sit. . .
female, left-handed, right side of the bed when alone mostly because because of an old injury to the left shoulder joint and left side of my neck. it’s more comfortable to lie on my left side than my right and it’s more convenient when stumbling into the bathroom in the dark.
during my togethernesses, the divemaster had the right side of the bed and later, the ex-fiance had the left side. hmmm. now that i reflect back on it, i sleep mostly with my back to my partners no matter which side of the bed i’m on. :dubious: