Knowing that are so many different brands out there, I am not going to focus on just one. There are many different applications and many different models available from the manufacturers. I've included links to the tool descriptions and some of them go to retailers. The others go directly to the manufacturers. I had to cut the Home Depot out because their site redirects me when I tried to use the links. Their site does provide pertinent information on specs and pricing. Buyer beware! Some manufacturers have been known to market a "promotional" line of cordless tools and then drop them. I have deep emotional feelings for Delta tools, but when they introduced a line of cordless tools several years ago, they sold them through the Christmas season and then they vanished. The batteries do not interchange with anyone elses so, they are useless when the batteries die. Try to focus on major brands with good reputations and long-running product lines when shopping for cordless tools.
Craftsman: Most of my experience with Craftsman has been with the 19.2 volt sets. They currently offer two different models. They are most positively identified by their color, black or gray. From the heart, the black set is by far superior. There are more tools available in the black line and the over-all quality of the tool, from the feel to the run-time is comparable to much more expensive brands offerings. I would recommend the black for anyone who wants a good cordless set for light construction or heavy weekend use. The gray might suffice for occasional use and light duty.
Ryobi: Not bad for the money. The Ryobi sets are incredibly versatile and are so close in quality to the Craftsman (I think they are made by the same manufacturer), that I would have a hard time deciding on one or the other. If you look at the Ryobi and then look at the Craftsman reciprocal saws, they are identical except for the color. It really boils down to what color do you like or where would you prefer to buy? The Ryobi is available with many more attachments and seperately available tools. The Home Depot is the best source around here for Ryobi and offers them at reasonable prices.
Ridgid: Another case of identity crisis? I am not sure if they are the same as the Ryobi and the Craftsman, but the quality is a little better. The Ridgid is in a tougher case than the others, there may be other advantages to them, Ridgid has a very dependable reputation to protect. They are available at Home Depot for a medium price above the Ryobi and slightly less than Dewalt.
Dewalt: 18 volt. Guys, Dewalt has become the industry standard out in the field. I have used these in nearly every recommended application and some apps that are recommended NOT to do. Unbreakable? No, I've seen 2 or 3 destroyed in different ways. One was impact related, one was burnt up from the inside (I did that one), one was just plain old worn out. These tools claim to have the longest run-time and the most power. It's hard to argue. I think the run-time is really exceptional, but I try my best to use my tools efficiently (when I'm not abusing them), not everybody knows how, or even what I'm talking about. You will discover the difference when the batteries start to run low. Keeping the drill running straight and not stressing the bits sideways, using a saw in an exact straight line, not trying to correct a cut midway through. If you can afford a Dewalt, you will not be dissapointed like you would be with a less expensive model. This is a professional tool and may not be necessary for an average homeowner.
Black and Decker Firestorm: Made,, well, SOLD by the same company as Dewalt. The comparison stops right there. Firestorm tools come in some good looking packages. From lawn trimmers to plain cordless drills. They are suited for the ocassional use that the average homeowner would need. NOT a professional tool.
Hitachi: The green monster grows. Several of the contractors I know have gone green. They offer the best warranty out there as far as I know. Run-time and charge time is comparable to the best and the more expensive tools at a closer to medium price. There is a limited selection of tools available though. They are good tools across the voltage spectrum.
Porter Cable: Maybe I just like the gray, maybe it's because Norm uses them, I like these. The 12 volt through 19.2 is very professional feeling and is comparable to the Dewalt and the other more expensive tools. The selection is kind of limited to drills and saws, but they do offer a router in 19.2 volt. I have the 19.2 volt hammer-drill and a circular saw. I like them both and use them for everything. I've used them side by side with Dewalt and Craftsman and the Porter Cable is just as reliable as the Dewalt, as light as the Craftsman and seems to have as much if not more power than either of the others. The Porter Cable tools are professional tools that I'd recommend to the pro or the homeowner who uses his tools regularly.
Milwaukee: I had such high hopes for these tools. As soon as I opened these tools I was shocked by their light duty looking bodies. I charged them up and started using them just the same as I would have any other tools. Soon though, I was bumming Dewalts off of the other contractors on the jobsite. The run-time was disappointing and I had an over-all bad experience with them. THEN they came out with this new technology! They offer a 28 volt tool that weighs less than the usual 18 volt tools! the run-time is phenominal and the power is UNBELIEVEABLE!!! As usual though, high quality and technology comes at a premium price. If these tools ever come down to a reasonable price, I'll be putting them to use in my arsenal of POWER tools.
Panasonic: Another company in the same market as Hitachi. Good tools looking for a foot-hold in a crowded market. If you buy these, you will probably not be disappointed. The selection of available tools is pretty small, but what they do offer is good, near, professional quality tools with a good warranty. They are used by pros who say that they are very satisfied with them. Deffinitely worth consideration when you get ready to buy.
Bosch: If Dewalt tools had a rear-view mirror on them, a Bosch tool would be right there. Bosch tools are every bit as good a quality as any of the other comparable tools out there. They are just a little harder to find. Professional quality at comparable prices. I would consider these for myself.
Makita: I feel the same about these tools as I do about Bosch tools. My first professional quality cordless tool was a Makita. It out lasted every other brand of tool available then and is a strong contender now as well. Professional quality, competitively priced, with features you might like more than the others.
Skil: See Black and Decker Firestorm. Not a professional quality tool, but a good value for the homeowner that will not use it every day to make a living.
As for flea market tools and discounted imported tool outlets, loosen up the pocket and get a major name brand tool with a reputation and a warranty. You will be ahead from the get-go. I included a link to a set of tools that I have no experience with, but this is the type of set that I avoid anyway.
Tom in KY, a carpenter/woodworker from way back.