Who could survive on Everest the longest

Poll

Probably Cap since he was frozen for years.
Ancient One if she can cast a spell to keep her going

When she was on Everest in DS the movie she showed no signs of reaction to the cold.

The Ancient One, lol.

Most likely the Ancient One via some kind of passive magic hax shenanigans. As Broly mentioned, she seemed completely unfazed (unlike Strange, who was clearly freezing his ass off) by it while up there in Dr Strange.

From around 1:45 odd mark onwards:

YouTube video

Steve could probably last a while as well, but I wouldn't really bet on him against a centuries-old master sorceress.

On a random note, that, "Oh no. Not again," always makes me chuckle. I wonder how many poor bastards didn't make the cut.

Ancient One legit tapped into an extradimensional force for immortality...

Cap might live as an icicle, but ancient one will probably be walking around.

Bane wins

Cap was a Popsicle for over 70 years; he can take it.

Bucky should be able to last too since he gets frozen sometimes for decades between missions.

Actually just thought about it. Ancient One should last longer as she has lived for thousands of years from dark energy.