As DeFlavor said, usually these questions are answered in the first few pages.
As Rocky says, for the occasional user Ryobi does fine. Ryobi batteries will have a have a shorter lifespan than the "Big Three".
DeWalt makes the biggest bang for the buck, their 20v tools are a good idea for guys who are want/need a cordless table saw,, miter saw, or a worm gear circular saw.
Milwaukee makes the best tool itself--ergomics, the plastic housing, bearings and races.
Makita makes the best batteries and most efficient motors , which are the heart of any cordless tool. With proper care Makita batteries will last longer than others.
Don't let the batteries freeze, they'll last a LOT longer. Fully charged batteries won't freeze as quickly, and fully charged batteries will have a longer lifespan under any conditions--don't discharge them and then toss the batteries in the corner and forget about them. Batteries are expensive and I have a feeling their about to become more expensive.
Milwaukee and Makita are now owned by the same capital management outfit, although they are each stand alone companies there is a bit of crossover with some tools.
