I waver up and down the channels between CN, Nicktoons, and Disney XD.
CN has definitely went in a fairly lame direction by forsaking their cartoon origins. Flippin' Turner Broadcast Media should have enough money to shell out for another station to air their crappy kid reality TV and old hit movie stuff. Ah well, they still crank out a few good series: Chowder, The Misadventures Of Flapjack, Venture Brothers, and lets not forget Johnny Test.
Nicktoons is sort of morbid since they primarily air old, awesome shows that they no longer make new episodes for: El Tigre, My Life As A Teenage Robot, Mighty B (they might still be making these), Ren & Stimpy (late night once a week). Wish they still aired Angry Beavers - alas, no.
Disney XD is a bit less Disney elitist than the main channel and fills a similar niche that Nicktoons does for Nick (airing the old but good) in addition to airing some high profile superhero shows of yesteryear (e.g. X-Men, Gargoyles, ect). I primarily watch them for Phineas and Ferb (relatively genius) Kid Vs Kat (rather young but clever slapstick) Jimmy Two Shows (oddly forgettable yet somehow enticing), Monster Buster Club (excellent CGI series, albeit a bit young). Their live action shows should be avoided like the plague - surreally, it's like they're the painfully cheesy pantomimes of real life and the cartoons are more realistic intelligent counterpart.