I've got both the Milwaukee M18 (Impact, Circular, Sawzall, Flashlight, Hammerdrill, Compact, Grinder) and Makita LXT (Compact Hammer, Impact, Reciprocating Saw, Flashlight, Grinder, Circular Saw) sets, with my father owning the DeWalt line (2 Hammers (Nano/Non), Compact, 2 Impacts (Nano/Non), Trim Saw, Circular Saw, Grinder, Reciprocating Saw).
In terms of battery life (3.0Ah batteries) and power doing a job, both the M18 and DeWalt Nano series outperform the LXT in my experience. The Makita LXT reciprocating saw is crap, the Milwaukee M18 is OK, and the DeWalt is my favorite out of the group (have a Miwaukee Sawzall for anything serious). I prefer the Milwaukee M18 6.5" circular saw out of the three companies. It's a tossup between the M18 Impact and the LXT Impact as my favorite, but the DeWalt is no slouch. I like the Makita Compact Hammer over the Milwaukee Compact Drill; I rarely use the Milwaukee Hammer Drill.
That said, my preference for lighter work (what I normally do) is by far the Makita LXT with 1.5Ah batteries.The ergonomics and weight on the drill/impact are simply amazing. If I need more power or am doing anything besides drilling/driving, I grab the Milwaukee 3.0Ah set.
If most major work is done, I opt for the Milwaukee M12 set (got the Drill, Screwdriver, Hackzall for $169 and the Impact free after MIR) for carrying around.