If there is one Dead Center that shoots in "the most" guns-- it is likely the .45 / 50 300 gr. That shoots an inch in the Austin & Hallecks, Savage 10ML with smokeless, etc., etc. It loads too hard in my Encore, however.
The Knights seem to like the .40 / 50 220 and the .44 / 50 300 DC. The Savage will shoot the Dead Center 40 / 50 240, 45 / 50 300, and 45 / 50 340s all sub-1" with smokeless. Toby Bridges found that the PR 275 / 300 / 330 QT's all shot well in his Savages with smokeless, and put those on his recommended load list as a result. The G2 Contender I have likes the 40 / 45 220 gr. Dead Center as well. Del Ramsey has shot deer with 195 duplex Dead Centers in his Omega, but he's hardly a believer in "as fast as possible."
So, there's not much really secret that I can see. Like anything else, it is just try as many bullets as you need to to get whatever level of velocity / accuracy you think you need. Barnes bullets have been historically painful for me to load, same with the 300 gr. SST's.
In jacketland, the 250 SST and 260 Winchester Platinum Tips have done well, with the 260 PT's the best-tested jacketed muzzleloading bullet out there-- by a huge margin. If I had to hunt with a jacketed bullet, the Platinum Tips would be it.