I'm no expert, but the body triangle offers better control and makes it harder for him to turn into you, whereas the hooks offer better mobility, which means you can switch to other subs than a rear choke. With the triangle, there's not really anything you can do except work for the choke. Also with the hooks you have a better chance to trap one of his arms. Lastly if you use the hooks you can use them to move your opponent around with your legs. For example if he starts getting too high on you, you can move him down with the hooks.
What are some good escapes from the triangle? I tend to get stuck in that position.