I use Dewalt (DCF887), but Milwaukee, Makita, even Hikoki (Hitachi) are decent.
If you're on the fence about which brand to go for, take a look at the other tools in their ranges and see if you might be buying some of them in future. That way, you can base your decision on the battery platform, rather than just buying an impact driver and realising later on that you wish you'd chosen a different battery platform.
Batteries are fairly expensive, so it's a pain to buy an impact driver from Brand A, only to realise, later, that you want to buy 2 other power tools from Brand C, and can't buy them naked/bare, because you also need to buy 2 or 3 batteries (and a charger) from Brand C, to go with them, since your Brand A batteries and charger won't help you.
Having said all that, I will just mention that the Hitachi impact is particularly nice to use because it has a triple anvil, rather than the more common double anvil. It doesn't make it any more powerful, but it makes it drive slightly faster and smoother, because you're getting 3 impacts per revolution, rather than 2. I've used it many times and really like it. That's not enough reason to choose it if you'd prefer a different battery platform, but if you have checked out other tool ranges and concluded that you don't care about the platform and just want a nice impact driver, then the Hitachi is worth checking out.
Another option, if you don't like the noise of impact drivers, is an oil-pulse driver (Makita), but they only have about 1/5th of the torque (40nm vs 200nm), so they might not suit your needs.
www.sgs-engineering.com
