@Kefkabot
I am an ass man: It is not about the size of the ass at all. Or rather, it is not completely about the size of the ass. It should be noticably big compared to the rest of the body, but you don't have to win the genetic lottery.
Unlike tits, which are the far inferior asset (pun intended), you can train your ass muscles and with the right training comes the right shape, form and firmness.
Large asses can be fatty, droopy molasses with craterous skin that just hang down or slap in the wind, or strong, musclelous, well toned pillows of lust that can crush your pelvis and dick in a heartbeat.
The above is true for both women's and men's asses btw
Now, 08A4's ass is great already. Page 2 of this chapter shows this once again; in the words of the moderm n day poet Doja Cat "If you can see it from the front, wait till you see it from the back back back back back".
However 04R1's ass is slightly perkier with less tendency to droop. Her whole body accentuates her ass much better and the whole thigh/ass/midriff ratio is much more well toned. Just take a look at the cover page; you can see exactly where the ass muscles end and where thigh muscles begin and how the latter compliments the former.