Over the top:
[ol]
[li]Clearance between TP and wall.[/li]
[li]Stress at the TP breakaway line is optimally outwardly directed; not always possible on under, frequently stressful, and besides, you can’t see the lines.[/li]
[li] Excessive spooling, as noted.[/li]
[li] Distance from user minimized with OTT[/li][/ol]
Ever corporate bathroom goes Over The Top, and since the janitors are paid to determine this, I accede to the pros. 
Well, I didn’t say whose individual preference, did I?
The important thing is that the paper gets on the damned spindle. There is NO excuse for propping the new roll on top of the spindle rather than throwing away the old cardboard and hanging the new roll. We won’t name names, but the guilty party knows who he is. Don’t you Dr.J.?
I once read in a magazine poll that men usually don’t really care, but 85% of women prefer the toilet paper to be hanging from over the top. I, being a woman, prefer it to hang from the top as well.
Yesterday, I pulled some off the roll a little too quickly. The paper was hanging from the back bottom, and due to gravitational pull and the momentum of the spin, the paper went out of control. Since I was busy wiping couldn’t do anything for that moment, I watched as the paper quickly piled up on the ground below. It took forever to wind it back up, and after I was finished, I hung the roll back on the dispenser the other way around.