Personally, I'd say the 357 Sig. Especially in the Gold Dot loading...you're getting +P+ performance and speed without +P+ punishment being poured out on your pistol. In fact, when Federal and Sig came up with the 357 Sig idea in the first place, they were doing pretty much the same thing that Federal did way back in the early 70's, which was to get a 9mm semi-auto round that would duplicate the performance of 125 gr. 357 Magnum loads coming out of 4" duty revolver, or get as close as possible.
When the Illinois State Police went to the all steel S&W 39 around '68, they wanted a 9mm load that went BOOM and would behave just like the 125 gr. SJLHP .357 Magnum did. And when they got the 9BPLE it did just that - I know because I used to carry it back in the 80's in a Sig P226. After a few thousand rounds, I quit shooting it because it started making my poor alloy Sig rattle a bit. However, I don't think the current loadings offered in that round are as hot as they used to be.
But nowadays you can get very, very similar performance to the 9BPLE with better bullet cohesion and less pressure smashing your gun's guts apart. For me, the 357 Sig is a win-win-win deal.
Just my $00.02.