The 3 starter polishers are the Griot`s Garage 6" (GG6), the Porter Cable 7424XP, and the Harbor Freight DA (HF). All will do the job. The GG6 is probably the most refined, and has the best warranty. The Porter Cable is probably the most common, is a good polisher, and is the second version of the polisher that started off the dual action polishing of car paint, and is a good all around polisher. The HF is the cheapest of the 5, is probably the most powerful of the 3 (in terms of being able to keep the pad spinning), but needs to have some accessories added, so the real cost will go up some. The HF needs a quality backing plate, which is an added expense, and most likely will need to have grease added, or replaced in the gear head. In return, you get the absolute bargain of the machine polishing world, often being able to be bought for as low as $49.95 (don`t forget to add in the cost of a good backing plate; don`t use the Harbor Freight backing plates or pads). Figure total cost for the HF, if you use a discount coupon, and get a good backing plate, at somewhere around $65-70. Still an excellent value. All of the polishers should be used with 5.5" pads.
I have a 7424XP, and it is fine for use for a DIYer. I started off with it; pads do stall, and it could probably use more power, but it gets the job done, especially if you are on your own time.
There are a lot of videos on how to use a DA on Youtube. I can recommend the videos by Junkman 2000; he has a 5 part video on how to machine polish a car for newbies that uses the 7424XP. Not everything he shows is correct, and some of it is more opinion than fact, but this video series is a great place to start. The video is applicable to all of the 7424XP type DAs (including the HF and GG6).
