Which team should the Bulls most fear?

The Bulls are playing so great that I'm not sure if there even is a team for them to fear. Nonetheless, if I had to choose, I would pick OKC. Russell Westbrook is a good defensive match-up against Rose (as he can match Rose in terms of speed), and he can also give Rose trouble on the offensive end. Ibaka and Perkins are also important for OKC, as they can provide a strong interior presence in the paint, which can limit Rose's penetration. They can also rebound, which is important against a Bulls team that thrives off offensive rebounds, and they can shut down Noah/Boozer with their defensive prowess. Durant is the biggest factor for OKC. The Bulls defense is designed to prevent opponents from getting easy shots inside the paint. Players like D-Wade struggle against this type of defense, as he is a player he gets a lot of his offense from driving. Durant, however, is able to dominate even against this type of defense b/c of his shooting abilities. It will be very hard, I believe, for the Bulls to contain Durant. Durant is, moreover, capable of shutting down Luol Deng w/ his height and long arms defensively. The Bulls may have the better bench, but in the playoffs, it's going to be the starting lineups that play for most of the game. OKC, besides, has the better bench PLAYER in Harden who can give the Thunder at least 15 pts of the bench. The Lakers, Heat, and Celtics are there, but I feel like the Thunder are the most poised to contain the Bulls defensively and produce points offensively.