I think you will find that you are going to get as many answers to this questions as you get replies….
I shoot 3 under and my bows are quiet.
I have never shot split so I don’t know the difference.
3 under is most accurate for me and it works best for me shooting instinctively.
I think what is most comfortable for you is the best. I was taught 3 under and that is what I prefer. I tried split to see what would happen and my shots were all over the place.
But, that is probably because I am not used to it and don’t practice it so take that for what it is worth.