I prefer Under BUT(T) there are always exceptions like the location of the dispenser, for instance (sometimes it is easier and faster to grab from the top rather than under the roll). And, fold the paper, not bunch! Bunching could lead to unexpected poke-throughage...
I was always an over until I got a cat. The benefits of not get an entire rolls clawed up outweighs anything else.
Printed/patterned paper is designed to roll over, not under.End of debate