No. Disney came and still is at a very close second (with Disney's own output, and The Fox Kids/Saban library, and others), to the more #1 superior Time Warner library, with the Warner Bros. Cartoons, the DC Animated Output, the Warner Bros. Animation library, the pre-1986 MGM cartoons (except the Pink Panther and Ant And The Aardvark), Hanna-Barbera's library, Ruby-Spears, and The Cartoon Network Studios/Williams Street library.
Fox was at third until 2001, when they (and Saban) sold its library (except the two Power Rangers movies, odd) to Disney. Now, they're fifth with the Fox prime time animated output, and some classic toons.
Viacom is third with Nickelodeon/MTV's animated output.
CBS is fouth with Terry Toons, and other cartoons, like Duckman and etc.