If you want a companion animal, a pit bull is obviously not the best choice given their well-established track record of violently unpredictable behavior, particularly regarding children.
If you want a dog to sound the alarm if those of ill intent are about, there are many small breeds that have been bred for centuries just to accentuate such characteristics. Any of them would be a better choice than a pit.
If you want an attack dog (for whatever reason) other breeds would be a better choice since pits were bred to be aggressive to other animals and not to humans. Problems arise when very young humans are perceived by these dogs as small animals.
If you want a hunting dog there are obviously many much, much better choices.
If you want a service dog there are many much, much more approachable, intelligent and trainable breeds.
The only role where a pit is the best choice is in dog fighting, which is a vile, utterly immoral, and indefensible practice.