Three-point shooting by far out of those two. It's getting as boring to watch as the days of pure isoball and contested long twos, and it's too overpowered. Even if there were more heated rivalries, the games would still be boring because of the style of play that's taking over the league.
The special Charmin-soft officiating that only the Warriors and Rockets get is worse than both, though. It used to be superstar calls, now it's superteam calls. Even superstars who aren't on teams that fit the league's desired marketing narrative don't get calls anymore, while role players like Draymond are allowed to do whatever they want because they wear a favored team's jersey.