I thought Tab Ramos was the best of that first generation, in terms of skill. Playing in Spain and then with an inferior cast in New York, plus injuries, probably made him less prominent here than Harkes (England / DC), but I thought Ramos was the better player.
Dempsey is doing things no other American has the confidence to try. He's probably had more success over the past couple of years than any other American. Of course, he's been my favorite since his days playing in New England, but I always thought I was watching him with homer bias when I thought he was the best of the current Americans.
I agree Donovan should be playing full time for Everton. That is a great match of player and team.
As for keepers, I sort of feel like I did when I rooted for Bird v. Magic. For years, I always thought Keller was the best, but I have to admit Friedel's accomplishments and longevity at this point has paased him.