The thing that I think about is that there is only one guy out of the four that has shown he is willing to play off the ball and do so effectively (Harden hasn't done that in 9 seasons and even then he dominated the ball with the second unit in OKC). So Russ and Beal have to get the nod. Also, I think Washington wants to roll with that duo and while Houston wants to keep Harden, he may make it untenable to do so.
Another thing to think about is that Westbrook and Beal will be in the East, so they'll face lesser competition and I just looked at the list of back courts in the East and unless you think that Trae and Bogdan are better than Russ and Beal... then the Wizards have the best back court in the East.
The West is a much different animal, more competitive teams, more really great back courts, you look at the West and the with the uncertainty surrounding Wall their could be 3 , 4, or 5 teams that have a better back court (Phoenix, us, Dallas, Utah and even LAC). Harden and Wall don't complement each other and we just don't know what Ball's game will be like since so much of his dominance was based on his elite speed and quickness.