As others have mentioned, these two are not really comparable, they serve different roles.
I would use an SKS for "battle", defending a neighborhood from looters, for hunting up to medium sized deer at reasonable ranges (with SP ammo), and for fun rifle target shooting.
I would use an M1 Carbine for in-home defense, for training new shooters (especially smaller stature and recoil sensitive), for hunting small game, and for fun short-range target shooting (not over 100 yards). With SP ammo (which was not available to the GIs who used it during wartime) it is a credible manstopper. It has been used by police forces that did not want to carry EBRs, and they reportedly "never had to shoot anyone twice". It might be a good bug-out-on-foot rifle because of it's light weight and the light weight of the ammo per shot, assuming you simply want to evac an area that is under "stress". It's more politically correct than an EBR or an SKS because of the lack of any "evil features", which may save you some hassles either now or in the future.
Different jobs, different tools. In a pinch they can be stretched to cover each other's areas, though not ideally. I already own 3 SKS rifles and plan to acquire 2 M1 carbines in the near future. I see a use for both types.