I don't think it's nostalgia to think that cartoons were better 5-10 years ago.
There were just some really good shows, that I liked as a kid.
Gargoyles
X-men: The Animated Series
Teenage Mutant Ninja Turtles
Batman: The Animated Series
Justice League
Alladin (seriously it was a good series, even got to end with a movie)
Thundercats
Samurai Jack
The few cartoons I watched this generation were The Spectacular Spider-Man, Wolverine and the X-Men, and TMNT (not the series where they go to the future, that was horrible.)
BTW, I chose to only include cartoons that were made for kids.
As for adult cartoon; Futurama, Simpsons, American Dad, Archer.