#1 Single auger juicers, both vertical and horizontal, will give the best results for watermelon. The juice will be very tasty, without foam, and there will be a lot of it. If you will be juicing mainly fruit and other soft ingredients in addition to watermelon, a vertical juicer is the best choice. If you want to juice root vegetables, choose a horizontal juicer. They are also the easiest to use and clean.
#2 Twin-gear juicers will give the same results as single auger juicers.
#3 Mechanical juicers - although they take some physical effort - produce high-quality juice.
#4 Centrifugal juicers are also suitable for watermelon, although the juice will be foamy and pulpier.