I feel like I can comment on this since my car has the "dreaded" Porsche black paint. Unequivocally, the best that I have ever used is Menzerna SF4500 (PO85RD). When you think you have gloss, just use this and you will see that you were sorely mistaken.
Now, there are some "new kids" on the block that have been challenging Menzerna for the throne. If a one step is what you're looking to do, I have heard that it is tough to beat SONAX Perfect Finish 4/6. Even those that would normally gravitate toward Menzerna PF2500 (PO 203) have said that the SONAX may be the best of the bunch. If you're needing to compound and then finish, SONAX also offers a more traditional two-step approach. I've also read that the SONAX Nano 3/6 is also a good burnishing/jeweling product, much like SF4500.
I have only done a two-step once on my black and it was all Menzerna: first FG400 and then SF4500 followed up. With any of these polishes I really don't think you could go wrong.
Happy detailing!