Here are two that compare wealth, showing the US 50th percentilers doing significantly better than European ones. US median wealth according to this is $162k: https://www.richmondfed.org/publications/research/economic_b....
And it's hard to get this data for Europe but looking at the "Median" column for this https://en.wikipedia.org/wiki/Wealth_distribution_in_Europe it looks like the US middle class would slot into fourth place, just below Denmark which is at 165k, and far ahead of say, Germany, which is at 65k.
Like one thing I realized is that it seems that you need to earn way more in the US to have a similar level of living quality/standard compared to the EU. As far as I can tell I probably would need to earn ~50% more to have the same quality of live level in the US compared to where I live now. Through it probably depends a lot on where you are in the US/EU.