Stainless is nice but carbon in general lasted longer and is easier to work with and refinish. Carbon guns generally can be mad tighter and don't have galling risks and Wilson parks them under the top coating. Also has a lower CF so will be less sensitive to lube and dirt.
Stainless has improved low temperature performance and better corrosion resistance vs untreated carbon and in extreme environments won't shatter unlike carbon steel. (Talking like -30 here if not more) I have a all stainless gun that is coated on top of the stainless and it's no different from my carbon guns since the coating is what everything is gliding on anyway.
If you had me pick I would likely do carbon since I shoot my guns enough the ability to repair and refinish easily is important to me. You can't weld stainless easily if you crack the frame. It also will rust quite easily if not coated unlike the common misconception that they are rust resistant, even in this sub forum there are plenty of people with stainless guns that have had surface rust issues just from a week of continuous carry.
I like the carbon, Wilson has great bluing, in-house and Baron, Turnbull.
I also like the Armour Tuff finish on the carbon frame. They parkerize under the finish to protect metal from rusting. Also if you wear the finish off, you can send back to Wilson and have finished for a reasonable amount of money. On my pistols, the Armour Tuff finish has held up nicely except for the ones that I draw out of Kydex holster.
The addition of carbon to iron is primarily what defines steel, any steel, including stainless steel. Without carbon, there is no steel of any kind.
The subsequent addition of chromium, in sufficient percentage, is then what primarily defines stainless steel.
In addition to bringing with it greater (but not close to absolute) resistance to oxidation/corrosion, chromium also affects other attributes of steel, and not necessarily in a wholly positive way. Rather obvious if one thinks about it ... i.e., if chromium had all good and no negative attached to it, then pretty much all steel produced would be "stainless"; there would be no market for anything else.
Chromium affects both machineability qualities and results in a higher surface to surface coefficient of friction. It might not chemically interact quite so well with treatments such as parkerization or blueing....the chromium "messes-up" the chemistry of these treatments. Some believe all of this makes absolutely no difference; some believe that it makes only insignificant difference; and some believe that any such difference matters.
On such matters of opinion, I suppose the only opinion that matters is one's own. And for some, aesthetics is all that matters...and that again becomes a matter of personal opinion.
In the event I ever buy another Wilson Combat 1911 it will be stainless steel. I don't want to suddenly find the AT finish I like can no longer be had should I feel the need to get that cheap easy refinish.