#1: Robotech (a tough battle with TMNT and Transformers, but no cartoon dealt with some of the more adult themes like Robotech did, God, that cartoon was amazing - closest thing)
EDIT: I am aware that technically Robotech doesn't count as a "Western cartoon" as it was mostly 3 different Japanese series combined to make one continuity. Although, I'm giving it that prestige based on the work that had to be done to make it all connect (additional cels, fleshing out a complicated storyline, VA and production being done in a SHORT amount of time, etc...it was almost a new show)
#1a: Transformers
#1b. TMNT
#4: X-Men (90s)
#5: JL (After seeing Starcrossed....it worked its way past Spiderman and some of the shows of nostalgia - Like G.I.Joe and M.A.S.K.)
Others:
M.A.S.K.
Jayce and the Wheeled Warriors
G.I.Joe
Ren and Stimpy
Voltron
Simpsons
Futurama
Bionic Six
BraveStar
SilverHawks
The Comic Strip
Spiral Zone
StarCOM
Captain-N: The Game Master
PPG
Spiderman (1st series, FOX)
2 Stupid Dogs (I've never seen a show capture "stupidity" better than this did)
I would like to see cartoons to go back to having rock vocals for theme songs. Man, the themes to M.A.S.K., TMNT, Jayce, and many others were so great. Cartoons ought to go back to what they were in 80s - being created for the sole purpose of making a toy line out of them.