Most Helpful Guy
Well, I am a US guy who married a European woman and have had American girlfriends in the past, so I guess I am well qualified to answer this, although this applies mostly to women from Germany, Austria, and Switzerland.
In my experience, European women are somewhat more sophisticated culturally and a little less materialistic, but they are also somewhat less open minded. They're also somewhat more liberal about sexual matters.
Most Helpful Girl
Some women are better than other women, no matter what nationality they hold. I know a lot of good and bad European women, and same goes for Americans