With the Nexus Ultra SI, you don't have to choose! It gives you the best of both worlds! It has a shaft framed in such a way that it massages the prostate while the rollerball gently rolls against the perineum.
You wanna go wild? This will make you go wild! Not only does it work wonders (giving it plenty a good reviews), it looks sleek and nice to boot (pun intended). Only the best quality and sexiest stuff for that hiney of yours!