Honestly Fat Balloon wasn't even in the top 5 as far as busts. Dude at least scored goals and played for a number of years in the league. His first 3 seasons with the Sharks were solid if not spectacular. played 12 years in the league. Plenty of Sharks 1st rounders never even made the show or only played a handful of games.
Teemu Riihijarvi was the worst all time and it ain't even close. Highest pick that never even played in the NHL. So bad Hockey-Reference doesn't even have a page for him.
The best ever has to be Nabby. Drafted in the 9th round. Rookie of the year, solidified the goaltending position for the most part for a decade.