Having most of the DeWalt 12 V Max, Milwaukee M12 line and all of the Bosch 12 V line I can state the DeWalt impact is stronger than the Boschs and the regular M12 impacts, from what I understand the new Milwaukee M12 Fuel impacts are the most powerful 12 V units presently released. If you have large hands the DeWalt's grips may be a little small, they are on me. Also when the XC or 4Amp hour M12 batteries are loaded into the conventional M12 impacts that are comparable to the DeWalt's. The Milwaukee and Bosch tools feel tougher, better built than the DeWalts, which feel very light.
This picture doesn't reflect my last 5 Bosch 12V pieces.
TheGrooveking