What type of car polisher is best?

For polishing a car's paintwork, random orbital polishers are best because the random nature of the pad's movement is less likely to leave buffer trails. RO Polishers which are battery powered are preferable as then you don't have to worry about dragging a lead around with you.

Having said that, other types of polishers might also have their place and their uses. We still have rotary polishers because it's useful to have something that is aggressive. We also regularly use small polishers for hard to reach places.