Went with Dewalt (3 speed impact + 2 speed hammer drill kit, including 2x 2.0A batteries) because the tools are generally cheaper than other brands but offer similar performance and quality (at least the tools that I initially purchased). Since then it just didn't make sense to go with other brands especially after I acquired a few more kits and a whole bunch of bare tools thereafter.
I do a little research and comparison before buying a new tool, yes Milwaukee offers a little more bunch (at least on paper, more on it later) but their tools cost more, sometimes much more. So really you are paying about the same $$$ per one performance unit (torque as an example). Sometimes Dewalt comes out better, sometimes its competitors. To better explain what I mean, a mid-range 1/2 impact from Dewalt (DCF894) produces 330 ft-lbs and costs $165 from www.mississaugahardware.com and from the same store, a new, mid-torque 1/2 from Milwaukee (2860) produces 450 ft-lbs (which is substantially more, at least on paper) but costs $279. All in all, you're getting about 2 ft-lbs of torque per $1 with Dewalt, and only about 1.6 ft-lbs per $1 with Milwaukee.
Now about my "on paper" comment - they all inflate the real output numbers of their tools, but from what I learnt over the years reading various reviews and comparisons, Milwaukee is generally worse than Dewalt.
In the end, even if the #s were true, Milwaukee has a little edge over Dewalt, but unless I was chasing the MAX numbers, I couldn't justify the price difference between the 2 companies (I haven't really considered other brands even though I've worked with Bosch, Makita, etc. - they were OK, just something about them didn't make me consider their line up.