For functionality, either is great, although in some cases Rugers may take a bit more extreme abuse (not enough difference to matter to most). Rugers absolutely have me won over with the Blackhawk series for vintage style and durability, especially if you want .45 Colt.
In terms of sex appeal and future resale value for most models, I have no doubt S&W wins hands down. You'll never see a mainline production Ruger having the kind of cache that old Smiths have. But since Rugers have less resale value, you end up getting lots of bang for the buck.
1944 Mauser byf K98 8mm, K31 7.5 x 55 Swiss, Rem M700 Classic 8mm, 1920s Colt New Service .45 LC, Browning Hi-Power and HK P7 in 9mm, SAIGA .308 22", SKS 7.62x39mm, S&W 686 Plus 6" and Taurus 617 2" in .357 Mag, Ruger MkIII Target 5.5" BB .22LR, Mossberg 500 & Marlin 120 in 12 GA, etc.