The fastest-growing trees are the ones that will need pruning more often. In the Front Range area, blue spruce, cottonwood, silver maple, catalpa, and white oak are among the fastest growers. Incidentally, white ash is also a fast-growing tree, but it is not recommended for planting because of the non-native pest emerald ash borer.
Furthermore, in addition to speedy growth, some of these, in particular cottonwood and silver maple, are famous for branch and limb breakage, especially during early-fall or late-spring heavy snows. If you have any of these types of trees on your property, you might consider a professional pruning service to keep your trees symmetrical and in good health.