Shadow all three before you decide, ideally in the specialty you think you want. Physicians carry final clinical responsibility and train the longest. Physician assistants train in roughly 2 to 3 years and can switch specialties more easily over a career. Nurse practitioners come through the nursing pathway and often specialize earlier.
If you want to be the one making the final call on complex or ambiguous cases, lead the broader care team, or do something like anesthesiology or surgery as the attending physician, the answer is MD or DO. If autonomy over specific decisions matters less to you than a shorter training path, it's worth seriously weighing PA or NP before committing to the longer road.