I think Seasons 1-5 of The Sopranos were solid. Though 1 and 2 stood out because of Livia. I can see why people think it slowed down a bit in Seasons 3 and 4. But it picked up again in Season 5. The weak season, in my opinion, was the last one. I've ranted about it again and again. Season 5 set up things perfectly for a normal 13 episode Season 6. But Chase let HBO's $ go for quantity rather than quantity. And much of last season was just treading water until the final few episodes when they had to quickly wrap everything up.