Amazon has been blowing out the griots garage 6 DA for stupid cheap.... 79 bucks for the 10' chord model on periodic lightening deals. Even at their current price, it's still a good deal and has more power than the PC. Griots backs it with a lifetime warranty. I couldn't resist that price and flipped my PC.
Megs new mt300 looks really nice and chemical guys just released the 10fx if you want to grab the latest gratest mid-price dual action orbital. (but your looking at $200)
if you want to go high end, look at flex and rupes.
If you get a 6", think about picking up a 5" backing plate. Most of the DAs correct better turning the smaller pads.