Such a hard question but I give the very slightest edge to breasts.
I love doggy viewing a great ass, pounding, slapping ass, testing the SP with thumb in or out and especially, the skin slap with a great bounce. Reverse cowgirl with a strong thighed SP is such a great view.
Then there’s missionary in which an SP take take the pounding when I see them titties jiggle and bounce is amazing. Grabbing and sucking breasts is hot. Even holding onto them during cowgirl is amazing.
Yet, I love Russian and find it more satisfying cumming on tits rather ass, especially when the tits wrap around my dick. This is what gives tits the very slight edge for me.