The Golden State Warriors set the NBA single-season record with 73 wins, topping the 1995-1996 Chicago Bulls by one win. Are the Warriors the greatest NBA team of all time? I'll leave that to the basketball experts but it's perhaps worth mentioning that the Bulls' 72-10 season came in an expansion season.
The Warriors finished with an .890 winning percentage. Of course, that's never been approached in baseball due to the different natures of the sports. The Warriors played in a league where seven teams finished below .400. In 2015, only the Phillies played below .