If only considering the two, I am going to go with Ruger. Built like tanks, for less money. One can always have the trigger improved if that is a big factor. (And oftentimes for relatively little expense.) And Ruger in recent years has been moving into the more "svelte" auto line.
May not like all of the lawyer influence seen on many guns these days, but one often overlooked .45 is the Ruger P345. Mine are great shooters, thin like a 1911, and did I mention great accuracy?
Smith has given us the IL, with some issues, and autos with a very different trigger. (Personally don't like either addition.)
Ruger has given use a new, much more concealable auto line, with some issues - issues that they have bent over backward to take care of/fix/preemptively for the most part on their dime and on their call.
I still buy used pre-lock S&W revolvers, but my last new semi-auto purchase was a Ruger. And that is what I am currently considering adding, another Ruger.
As a parting thought, I still have to give a thumbs up to Colt. Still American made and made well.