1) Breaking Bad doesn't have an annoying, repetitive voice narration about the ethics and morals of what Walt has done/will do.
2) Breaking Bad doesn't get too pretentious.
3) Breaking Bad rarely has filler episodes, and when it does, they're actually interesting. E.g. Fly.
4) Breaking Bad's quality has remained consistent. *cough* season 4-8 of Dexter*cough*
5) Walt isn't an unrelatable, sociopathic (he does bad things, but he does them mostly for his family, and the fact he got f*cked over by Grey Matter) f*ckwit.
6) Breaking Bad has a few irritating characters, but they pail in comparison to that thunderc*nt Debra.
It sound like I despise Dexter, but I don't. I actually think it's a solid show, but it's nothing compared to Breaking Bad.