Hey MayanTraditions.
My personal pick (not just cuz Amaz**n says so) is right side.
I was visiting a Monks*er site the other day, and (after years as a webby) couldn't figure out where the heck the cart was...it was on the left. Checkout was on the left and dupped up top. I swear I was sitting confused.
Imagine buying a car and learning that the pedals were reversed...it would take a while to get used to the difference. With conversion, most dont have the luxury of a "while" (unless that while is a millisecond).
I personally like the look of carts at top/right, but wouldn't do it myself.
Just my 2 cents--right, wrong, or indifferent--thats my story and Im stickin' to it!