There is no single genre that is "best" for a beginner learning to play the saxophone. The saxophone is a versatile instrument that is used in many different genres of music, including jazz, classical, blues, pop, and rock.
As a beginner, it's a good idea to start with simple pieces of music in a style that you enjoy. This can help you stay motivated and engaged with the instrument as you build your skills. For example, if you enjoy jazz, you might start with simple jazz standards like "Autumn Leaves" or "Summertime." If you prefer classical music, you might start with simple pieces by composers like Bach or Mozart.
It's also a good idea to work with a qualified teacher or instructor who can provide guidance on the best pieces and exercises for your skill level and interests. A teacher can also help you develop good habits and technique, and provide feedback on your progress as you continue to learn and grow as a saxophonist.