Hello,
I am graduating soon too. I did an OR rotation and an ER rotation....
First let me say do what you think you will enjoy, don't start in a job you will hate, otherwise what is the point of being a nurse and going through all the school to have a job/career that you love.
However, I really don't recommend the ER, because although patients can be asleep most of the time and not busy, my personal 11 week experience was that when it gets hectic you have multiple tasks to remember and coordinate with the rest of the team. Also sometimes when it super slow you end up with the boring jobs and as you said "butt wiping".
I think the OR would be a great place for you to start given what you have stated. Your patients can have long or short surgeries, but it will be new people all the time and you get to concentrate on one patient at a time.
I wish you luck and I hope to find my niche as well