Hello my little demons!

As you might know, i wanted to draw Nagatoro's sister about the situation below (Image), but i have a question.
Which scenario could be hotter?

Senpai licking Anetoro's asshole while Nagatoro is just waking up, OR Nagatoro licking her asshole with Senpai watching in front of them?

In each case, the not selected one is going to be watching in the background...
Let me know y'all opinions or ideas if you have any! ;)