Since the days of 2E my favorite dragon type has the been the Greyhawk/steel dragon. Unlike your typical dragon that has a lair in the wilderness, Greyhawk dragons prefer to live in large cities. Able to shapechange into humanoids, they live among the population. They enjoy art and sometimes will serve as patrons to artists. These dragons tend to be neutral, not really committing to one side in the good/evil spectrum. In 2E they had a more wyvern-esque appearance. In later editions they were made to look more like typical D&D dragons. I personally didn't like this as I preferred their more unique appearence.
I always thought it would be fun to have a thieves guild ran by a Greyhawk dragon.
One of these dragons was mentioned in the Hall of Fame in the 4E Draconomicon: Metallic Dragons. You can read the excerpt here.