To this question there is no simple answer.
You can't say top or bottom just because you think that either of them feels rigt for you.
It's a lot of different factors that has to be considered.
The quality of the paper.
Is it one, two, or three layers of paper?
Is it a soft cosy paper, or is it like sanding your butt when you use it.
The location of the paper.
Is it on the right or the left side?
Is it infront of you or do you have to turn and almost fall of the toilet to reach for it?
Is it attached to the wall or does it stand on the floor?
The hight of the toilet.
Can you sit on the toilet for a good while without loosing the feeling of your legs?
Is there a bidé in the bathroom/toilet?
Do you have access to wet wipes?
Last but not the least.
How is it constructed?
A
B
These two different technical solutions leave no room for personal feelings.
You can place the paper how ever you want to but in the end it'll only work if you place it their way.
//Bell (on the toilet, with no feeling in the legs, the paper on the left side, standing on the floor,two layers soft and cosy paper, from the top.)