I don't wear a watch but a bracelet (if I wore a watch it would be the same as I'm now used to it), and I wear it on my left. I'm a righty, I like to have that wrist with nothing on it because I use it and it won't be likely to bang it on something.
I used to wear it on the left, but I now wear a Tissot mens watch and its big and heavy and wear it on the right hand. This way the things that sticks out on the side don't hurt my hand when the watch moves. I'm a righty