Is a 1940 Frigidaire freezer much better than a 2020 freezer?

In virtually every possible metric you could offer, the new freezer will be far, far better than the 1940 unit.

The one place a vintage appliance will walk away from the new ones will be in style.  Dang, but some of those old household appliances were attractive.  Now most appliances are just a big, essentially featureless box and that's all fine and good. It keeps prices down.

I've seen a couple of older units that have been thoroughly rebuilt and refurbished and repowered with new compressors and fans, and the work is genuinely brilliant.  I could probably do it, with some competent guidance in the finishing.  The mechanical work is in my reach.  But given the option between an old freezer and a new one, I would WANT the old one because it's gorgeous...and then take the new one because it is far more efficient, far more reliable, far more effective at keeping my food cold.

Because that last bit is the important bit.  Everything else is secondary.

If it is still working, it will be sucking up much more energy to run then anythign built in 2020.  But, anything built in 2020 will be made out of cheaper, thinner, weaker materials with many more bells and whistles built in to control the unit. Which means a much higher chance it will break down in some manner.

NO it is not . modern day freezers are much more energy efficient 

Frigidaire is the Electrolux Group's largest brand in North America. ... In 1926, the refrigerator design was changed to the more familiar all-steel style for which Frigidaire is ... Frigidaire ad - 1940 ... was acquired by White Consolidated Industries, which was then purchased by Electrolux in 1986. ... Electrolux October 16, 2020

bought a 1950s fridge and a used zenith ( made 1991) color set,,80 bucks cost incl delivery,,in 2003,both still kickin  old is gold

In 1940 they did not have frost free so you would have to defrost the freezer every once in awhile to get out the ice.  They are so so.

The 1940 freezer was NEVER as efficient as the 2020 freezer was when first built. As for reliability, I suspect the 1940 freezer was more reliable in 1940, but probably isn't in 2020.

If your comparing 1940 fridge in 1940 to 2020 in 2020.  I'd say 1940 as they built stuff then an it lasted.  There still out there running. Can be dangerous but thats only if you climb in a shut the door. (darwinism) 

2020 fridge will probably die by 2030 2035.

But fridge from 1940 in 2020 I'd probably take the 2020 but that 1940 one still might out live it.  Course if you wanted a 1940 fridge made in 2020 the price would be ridiculously high.

No. The new models are cheaper to run.

The skin is thick as a tank and hard to dent, but it uses a heck of a lot more power to run.