No. 2: Tracy McGrady
Say whatever you want about the Toronto Raptors during their first handful of years in the league, but they absolutely knew how to draft. Damon Stoudemire, Marcus Camby, Vince Carter and Tracy McGrady were the team's first four first-round picks, all hits.
That also was part of the problem, however, as the Raptors in the late 1990s had a pair of shooting guards who both deserved minutes and opportunities. Vince Carter joined the team a year after McGrady and immediately started, winning Rookie of the Year and even receiving an MVP vote, then made an All-NBA team the following year.
That relegated rising star McGrady to a second-fiddle role, and it wasn't one he was comfortable filling. The idea of T-Mac and Vinsanity pairing up and destroying the Eastern Conference was a tantalizing one; both were athletic scoring wings who brought it on defense as well, and the two could have found a way to coexist on the wing. In McGrady's own words, in fact, he believed they could have contended for championships.
Instead, McGrady hit free agency in 2000 and booked it out of town, signing with the Orlando Magic. He became a perennial MVP candidate and twice led the league in scoring, although he never made it out of the first round of the playoffs. Carter and the Raptors would win a series even without McGrady; imagine what could have been if they had stayed together?
Instead, McGrady left for more touches and ended up regretting his Toronto departure.