When judged by winning percentage, the NBA's home-court advantage is easily the strongest of any major North American pro sport. Since the league added the Charlotte Bobcats before the 2004-05 season, NBA home teams have won almost exactly 60 percent of their games (compare that with the 54 percent you see in baseball, 57 percent in football and 55 percent in hockey) and by an average margin of 3.2 points per game.
In part, this is thanks to the fact that winning percentage reflects a higher proportion of true skill in basketball than in other sports. When the better team wins more often, and there are systemic effects in place that cause home teams to be better (including officiating bias), it's only natural to see home teams have more of an edge in a sport such as basketball.
But although we like to think of each team having a unique home-court advantage, most teams' specific home-court effects can be reliably accounted for simply by using the aforementioned leaguewide average of 3.2 points per game for the home team. Over the same 2005-13 period, only the Utah Jazz, Denver Nuggets, and Golden State Warriors (each of whom had very large home-court advantages) and the Brooklyn Nets and Minnesota Timberwolves (who both had very small home-court advantages) had home-court effects that differed in a statistically significant way from the overall league average.
In particular, Utah and Denver were major outliers. Statistically speaking, there's only a 1 percent chance that the difference between Denver's observed home-court effect of 5.5 points per game (after accounting for strength of opponents) and the league average of 3.2 happened because of chance alone. Utah's 6.2 PPG effect is even more remarkable -- the odds of its true home-court advantage being merely the league-average rate are 1 in 1,278, or 0.08 percent. In other words, something is clearly afoot in Utah and Denver that causes those team to have an extremely pronounced home-court advantage.