if 5 largest economies all drop 50%, which of the 5 is most likely to recover quickest...the US, some may not recover at all
Actually it would probably be Russia. Russia is probably the most self sufficient country in the world right now, and has almost no debt, last number I saw was around 15% of GDP. Here's Russia's top 10 exports for 2021:
Mineral fuels including oil: US$211.5 billion (43% of total exports)
Gems, precious metals: $31.6 billion (6.4%)
Iron, steel: $28.9 billion (5.9%)
Fertilizers: $12.5 billion (2.5%)
Wood: $11.7 billion (2.4%)
Machinery including computers: $10.7 billion (2.2%)
Cereals: $9.1 billion (1.9%)
Aluminum: $8.8 billion (1.8%)
Ores, slag, ash: $7.4 billion (1.5%)
Plastics, plastic articles: $6.2 billion (1.3%)
So they have all the raw and intermediate materials they need "in house", they really don't need much of anything from elsewhere to get by.
Russia is also no slouch in the tech area. The only way to get to the space station until 6 months ago was on Russian heavy lift rockets. And Russia actually manufactures their own phones and computer stuff. Where is your phone or computer made?
I'm no huge Russian fan, but to under estimate them and over estimate our own capabilities is foolish.