Season 5 of Breaking Bad is the best season of the show, despite the admittedly undercooked Nazi prison gang villains.
Each episode is masterpiece after masterpiece, featuring some of the most memorable moments of the entire show (spoilers) the train robbery, taking out the police station with magnets, Walt's exile, Jessie's imprisonment, that meeting at the restaurant between Walt and Hank, Jessie revealing how he was joined his support group to sell drugs, etc.
Everyone talks about how Ozymandias was the best episode of the series, but in my opinion that honor goes to 51. Skyler might be the most underappreciated character In the show. Her guilt as an accessory to Walt's actions as a drug kingpin have been building up since season 3 and with this episode have reached the boiling point.