Kaplan Medical is indeed a well-regarded and popular option for USMLE Step 1 preparation. They offer comprehensive study materials, including live and on-demand lectures, question banks, practice exams, and study plans tailored to individual student needs. Kaplan's courses are known for their structured approach and high-quality content, which many students find effective in preparing for the Step 1 exam.

However, while Kaplan is highly recommended, the "best" prep course can vary depending on individual learning styles, preferences, and needs. Some students might prefer other resources like UWorld, BoardVitals, or Doctors in Training, among others, as they might align better with their studying methods or cover specific areas in more depth.

It's often beneficial for students to research and consider factors like course content, flexibility, cost, user reviews, and their own study preferences before choosing the best USMLE Step 1 prep course for their needs. Many also benefit from combining resources or using multiple study materials to create a more comprehensive study plan.