Good question. I thought an ileostomy went on the right and a colostomy on the left unless there were circumstances preventing that placement.
Mine is to the right and a little above my belly button. I know most are lower, but I actually wanted it higher, so I could see and reach it better. Also, I am right handed and for me it seemed it would be easier to work with using my right hand and not having to reach across my belly to get to it. I am a Grandma, so I wasn't concerned about wearing clothing or a bikini which would have made a lower placement more beneficial