I am a 5'3" 120 lb female who is looking for the best motorycle for a beginner, preferrably lightweight.

The Honda Rebel is a good choice, and inexpensive. You might also want to check out the other 250cc motorcycles that are out there - if you can sit on it with your feet flat on the ground you will feel much more comfortable than if you are on your tippy-toes. But at 5'3" you shouldn't have much trouble. Happy riding!