My favorite animated dogs would be...Densuke from Denno Coil, Mr. Tadakichi from Azumanga Daioh, Snoopy from the Charlie Brown cartoons The talking dog from Powerpuff Girls, and Santa's Little Helper from the Simpsons.
I don't know if anybody mentioned this yet (I did a quick check), my favorite dog would be Spike from Rugrats. He was a very good dog, and he always hung out with them. He was their hero .
Then from Pokemon I would have to add on Growlith and Arcanine. They were probably in my top 5 favorite Pokemon list.
Brian Griffin (Family Guy)- I like him because he's the smartest and most mature member of the Griffin household. He reminds me of my brother, in a way.
Dogbert (Dilbert)- An opportunistic, self-centered talking dog con-artist who operates several successful businesses and beleives that everyone else on the planet is there for his amusement. What's not to like?
Here's a little list of mine (incomplete cause I'm lazy to think up more), in no particular order, some good and some bad guys cause the good guys annoyed me way too much:
Blitz (Road Rovers)
Fu Dog (American Dragon: Jake Long)
Monroe (The Life & Times of Juniper Lee)
Patch (101 Dalmatians)
Thunderbolt (101 Dalmatians 2: Patch's London Adventure)
Brian (Family Guy)
Steele (Balto)
Buster (Lady & the Tramp 2: Scamp's Adventure)
Ace the Bat-Hound (Krypto the Superdog)
Tusky Husky (Krypto the Superdog)
Roscoe & DeSoto (Oliver & Company)
Itchy (All Dogs Go To Heaven)
Carface (All Dogs Go To Heaven)
Odie (Garfield)
Houndour & Houndoom (Pokemon)