#3 George Karl
Record: Regular Season: 1175-824 (.588), Playoffs: 80-105 (.432)
George Karl coached in the NBA for 27 seasons and missed the playoffs only 5 times. Karl shot to fame as the coach of the Seattle SuperSonics. He averaged 59 wins a season in Seattle over 7 seasons and reached his zenith in 1995-96, winning 64 games. There was just one problem, they ran into the 72-win Bulls team in the NBA Finals and lost in 6 games. Tensions with management led to his departure in 1998.
Karl then joined the Bucks, a team which hadn't reached the playoffs in 7 years. He led them to the playoffs in his first 3 seasons which culminated with a Conference Finals loss to the Nets. However, after 2 disappointing seasons, he was fired and took over the Denver Nuggets. He would make the playoffs every season, but only got out of the 1st round once, a common theme throughout his career. His last coaching stint with the Kings was very disappointing and he was fired in 2 seasons.
Karl had plenty of flaws. He often blasted players in front of the media and had a few run-ins with management. His playoff record is often questioned for all his regular season success. But he is undoubtedly one of the most adaptable coaches we've ever seen. From a hard-nosed defensive team in Seattle to an offense-oriented Bucks and his Nuggets were an incredibly high paced team too.