10mm because there's no practical way to suppress revolvers and I don't like shooting unsuppressed.
But I'm glad it's not a choice I have to make! I may not shoot the wheel guns as much for the above reason, but I do still enjoy them, especially just looking at and handling. All of mine are Smiths, a 28-2, a 19-4, a 586-4, 686 no dash and a 360 PD.
On that note, this is in the handgun forum, so we have to consider that there are only a handful of autopistol options for. 357, most of those pretty specialized and often impractical things like the Desert Eagle or Grizzly. But the equation changes a bit with rifles, my Marlin 1894 .357 with subsonic 158 gr .38 special loads being one of my most favorite suppressor hosts.