In my experience virtually all the Euro legacies are streets ahead of the US big 3 in terms of product.
I'd rate DL 1st, UA 2nd and AA 3rd of the US 3. They spent eff all on their cabins and fleets for years and it was really showing (record profits though).
All 3 are spending big bucks on their product now, but UA aren't touchng up the 757s
afaik.
As for EI there's a big difference between the experience on the 330s and 757s, never had the "pleasure" of the OAE 767 ex SNN, and hopefully never will.