Look at what each weapon was designed for. The SKS is handy, but still large. It had a role at one time as a battle rifle, not just a carbine, but a main line weapon, unfortunately replaced by the AK
. The M1 Carbine was designed as a light weapon for back area troops. It didnt "need" a big cartridge or similar because it was designed to have very very low weight (especially compared to the SKS). Either weapon will do well, considering SHOT PLACEMENT! This will soon degerate into another "whats a better caliber" war. Learn the weapon back and front and learn to combat with it. Wont matter what caliber it is then.
The weapons themselves: SKSs have fixed mags. Not terrible, however, there has yet a detachable (even the Tapcos, which I sold off to a mall ninja as fast as I got them) mag made that is reliable 100% of the time with the SKS. All M1 mags (even the foriegn contract ones) are reliable, cheap and can be easier to tote (no crazy bill hanging off the front), not to mention higher capacity. The SKS may have more range than the M1, but accuracy out to a combative distance would be almost equivalent. Downrange energy, well, thats for the physics profs to decide. While neither weapon has alot of "recoil", the M1 could theoretically stay on target easier and would be more controllable shooting some starving criminal rapidly. The rate of fire (semi) would be more accurate with an M1, but the SKSs cartridge would have more oomph at close range.
As for cost, only collectors are the ones commanding such high amounts on the M1 because it has all the parts from one company or what not. I hate that with a passion. So what if it has all the original parts from the Rockola company? Does it shoot? Then Ill give you the real world value for the gun, not someone drummed up by people that never shoot and think of weapons as commodities rather than critical assets. Someone comes up to me and spews how much their gun is worth because its a "X" (X being whatever made up value the weapon is percieved to have) will only get a so what from me. Just shoot the darn thing!
I wouldnt have too much of a preference towards one or another. Neither uses a cartridge that I would consider reliable in supply (you can get them both, but one is mostly from import sources, some american. The other is in limited supply, but available still from the CMP at the worst situation). I would probably go with the M1, seeing as I would have to tote the gun, plus in Katrina, there wasnt much firing anyways (there was some shooting, but limited). The weapon would be more of a deterrrant (the original idea for the M1) than a piece of weapon.