Let me first say, that my experience with domestic American Y is limited to US, UA, AC and a great deal of CO.

The hard product is pretty much the same, but the American airlines take a small win in my world, in that many domestic US routes often have IFE (Direct TV is awesome), but when it comes to the soft product the treatment is much better on European carriers.
Most will offer you a small meal of some kind and beverages for free, including alcohol, and no European airline afaik (except LCCs) charge for checked luggage.

Generally I don't feel so much as a second class passenger on a European Y as I do on an American Y, where everyone with status seems to be upgraded* and you have to pay for EVERYTHING - even head phones. I often feel like I'm actually in a LCC in the US when I'm in Y, where you will most often find me. I don't feel that in Europe - yet (some are moving in that direction).


*)Most European carriers do not automatically upgrade to C or F if there is availability as in the US (one exception is Czech Airlines, who do).