I used to buy dewalt 18v. Had an 18v sawzall which I never had any problems from. One drill, which I got for a good deal, somehow got stuck in the on position while drilling with a 1'' bit. The bit snagged and the drill wouldn't go off. The smell of burnt motor filled the upstairs and my battery quickly fried. Next 18v drill was an XRP 3 speed hammer drill. Very nice. A couple of teeth broke on the gears and it wouldn't work correctly. Took it in for repair and $75 later it was working almost like new. 3 or 4 months later the gear stripped again and friggin thing also didn't like to switch between hammer and regular. That's when I stopped buying dewalt. IMO, overpriced and not worth it.
I get the Ryobi stuff now. It's cheap and gets the job done. If it breaks, $39 will get me a brand new one. I've had an 18v ryobi drill now for 2 years and never had a problem with it. My only complaint is that the batteries don't last very long. But hey, $39 will get you 2 more to have on hand, ready to go. 1 dewalt battery will cost you twice that. Plus, ryobi has a huge selection of different 18v cordless tools to mess around with.