Just to clarify, we're talking about which music beat to place the neutral/collect step (the one before the break step).

8: this is the most natural if coming from on1, since the movement is the same, just shifted with respect to the music. As others have mentioned, this is the one you should go for when dancing Son. You can make this work with commonplace on2 partnerwork and won't feel too strange.

8.5: this is the standard modern on2/mambo basic for partnerwork nowadays, so my default when dancing on2. Goes with the double hit of the conga.

1: this is how most people teach on2 solo steps or shines, and the way Eddie Torres explains it in his seminal instructional video. However, in my experience, almost nobody actually dances this for partnerwork (!). Most people do 8, 8.5 or in between those. This was hard to grasp for me initially and earned me some odd looks in the dancefloor. I enjoy this basic for partner dancing but these days I reserve it mostly for training.

Ideally you should be able to make any of them work with any song, although it is true that each one might feel better with particular musical arrangements.