Main Reasons:
Beautiful visuals
Along the journey of 5 seasons , we get to see a lot of stunning visuals which are a treat to watch on the TV screen. The rich countryside
Characters
The show has given a lot of memorable characters each with perfect actors to reprise the role . walter white -> A high school chemistry teacher to a drug lord
Narration
The story gets into our head like slow poison. it's almost imposible to have just one favorite moment in the entire thing.
The Closure
The series ends on a high note. The lead walter white happily dies. The series comes a full circle ;its not open ended as many other series . You simply cannot give a better closure than the expression of walter white .