This is a good question! I think it depends on where you are at in your career, and what sort of things interest you. As a veteran police officer, I like the intersection of enforcement and trial. . . . making sure all the "elements of the crime" were proven, all the I's dotted and T's crossed. As a rookie, I enjoyed catching bad guys and making traffic stops. There are so many other areas! Planning a raid, for example. Or going undercover. I enjoyed being a Field Training Officer, but never considered being a classroom instructor. There are also supervisory and management positions, which, a lot of us don't think we will ever be working on budgets when we become a cop, but, somebody has to do it, and, it's better if it is a person with a badge than a civilian who has no clue what we really need! (slightly biased opinion, not intended to offend civilians!)
As you progress through your career, your interests will change. Each assignment will awaken in you something you had not previously thought about. You will use it as a stepping stone to the next position. It all builds upon the previous assignments!