.22-250 is slightly more efficient.
.220 Swift will give the highest velocities.
.22-250 is slightly easier on brass.
.220 Swift feeds a little more reliably.
.22-250 is easier to find brass for.
.220 Swift is less temperamental.
.22-250 stands out from .220 Swift with heavier bullets (60+ gr -- the Swift just doesn't handle the heavier stuff as well).
.220 Swift stands out from .22-250 with "laser beam" bullets (30-40 gr -- if you want the speed that comes with those bullets, the Swift is king).
Your barrel will determine accuracy potential.
Both cartridges are capable of sending thousands of rounds down the pipe without "burning out" the barrel, as long as the shooter is responsible and not abusive.
I had a circa-1983 Ruger 77 in .220 Swift that I rebarreled for a 6mm wildcat. That original Swift barrel had an estimated 3,600+ rounds through it, and was still performing very well (it had been in my family, since new). It was still going strong, but I was done with it and sold it. The new owner stripped the copper fouling from the barrel and was surprised to find what he considered to be a "like new" throat and rifling. He was absolutely ecstatic about the condition of the barrel, since he was using it to salvage his own burned-out M77 .220 Swift.
If you don't get the barrel scorching hot (and don't keep shooting through it at that temperature), they can last for a long time.
And if accuracy starts to degrade... strip the copper, before assuming the throat is eroded, the crown is damaged, or some other mythical failure has occurred.
As for my preference...?
Well, I have already made that decision: I went to 6mm cartridges.