Who's better... Ford or Chevrolet? Answer is as broad as the person's involved. However, you asked on a Dewalt forum. The answer you will find here will be mostly biased towards Dewalt for good reason. So without being to biased.. let's breakdown the facts and you can decide for yourself.
Dewalt has not changed it's 18v battery compatibility platform since 1996. Milwaukee has changed it's platform 3 times in the last 5 years none of which are compatible with one another. Dewalt compact batteries will fit all Dewalt 18v tools, Milwaukee 18v compact batteries do not. Dewalt currently has the largest 18v platform, larger platform means a larger variety. Dewalt also has a radio that will charge it's batteries. Milwaukee does not.
Dewalt has a 3 speed all metal transmission which gives you a broader range of application speeds. Dewalt's clamshell is made from Xenoy plastic. Milwaukee uses a ABS plastic clamshell. Dewalt uses a Rohm self tightening chuck for better bit retention. Milwaukee uses a Jacobs ratcheting chuck. Dewalt's motor is made from
Neodymium Iron Boride rare earth magnets. This material is currently the strongest type of permanent magnet. Milwaukee uses a lower grade magnet. Dewalt handle grip is 360 degrees adjustable. Milwaukee uses a three position grip, and if tightened to hard, or dropped can cause the handle grip to break off from the body. As Joomla responded, Dewalt uses better battery chemisty and a better warranty. It's not prorated like Milwaukee's.
As far as Impacts are concerned, I personally do not like the Milwaukee Impact driver. It's bulky, top heavy, overheats under minimal use. The quick connect on the Milwaukee is very small, and not pleasant to use.
Those are just my thoughts...
