My favorite are:
Tom & Jerry
X Man
Spider man
Batman

I have more than 700GB of cartoons :)

My favorite is Duck Tales, but my ever-growing collection includes:

Addams Family [1992-1993]
Adventures of TinTin [1992]
Captain Caveman and Son [1986]
Captain Caveman and the Teen Angels [1977]
Chip 'n' Dale Rescue Rangers [1989-1990]
Count Duckula [1988-1993]
Darkwing Duck [1991-1992]
Dastardly and Muttley in Their Flying Machines [1969-1970]
Disney Shorts [1925-1954]
Duck Dodgers [2003-2006]
DuckTales
Family Guy
Flintstones
Futurama
Garfield & Friends [1988-1994]
Huckleberry Hound [1958-1961]
Inspector Gadget [1983-1986]
Jetsons
King Of The Hill
Littles [1983-1985]
Looney Tunes [1930-1968]
M.A.S.K [1985-1986]
Magilla Gorilla [1963]
Peanuts
Pinky and the Brain [1995-2001]
Quack Pack [1996]
Raccoons [1980-1991]
Rocky & Bullwinkle [1959-1963]
Scooby Doo [1969-1978]
Simpsons [1989-]
Smurfs [1981-1989]
Snagglepuss [1960]
South Park [1997-]
SpongeBob SquarePants [1999-]
Star Trek [1973-1974]
Talespin [1990-1991]
Thundercats [1985-1989]
Tim Burton's The World Of Stainboy
Tom and Jerry [1940-1967]
Wacky Races [1968-1969]
Yogi Bear [1958-1988]

Pinky n the Brain.
anamaniacs
inspector gadget

Ozzy and Drix
Spawn
Wildfire

and my alltime favorite, The Pirates of Darkwater..of course it was canceled before they ever found those lost 13 treasures :(

Hey Arnold
Dexter's lab

Alright then

The Big O
Cyborg 009
Outlaw Star
Dragon ball
Dragon Ball Z
Yu Yu Hakusho
Dexter's Laboratory
Courage the Cowardly Dog
Almost all the Gundam series

South Park!!

By large and far, The ultra glorious Pink Panther!