who makes the best ones?
My experience with cordless tools is that basically they are all the same. The bigger question that I have had issue with is which ones have the cheapest replacement batteries? All of the cordless tools that I have owned over the past number of yeas have ALL been retired due to old batteries that would no longer take a charge (tool was still good). Then when I tried to get replacement batteries I would find out that they were discontinued or the price was more than what a whole new tool could be bought for. Just my 2 cents worth but that's what I have found to be true.
I have been gravitating towards Milwaukee tools recently but I have some Bosch tools too. I really think Milwaukee has more cordless tools for mechanics than other companies. I like their grease gun (I am eyeing up the newer 18 volt version but my 12v will have to work for now). I recently purchased the one handed 18v Milwaukee sawzall...its much nicer than the 2 handed version. I also have one of the Milwaukee heated jackets and it works great. As far as batteries go, I have gone to all lithium batteries. And when the time comes for battery replacement comes there is a guy around here that will replace the cells in the batteries for much cheaper than a new battery.
I personally like them all for different things. Can't beat a dewalt drill, milwaukee makes a impact driver that has some torque to it, Ridgid has great prices for the quality, and makita has a good solid line. If I were to go with a kit it would be the Makita, though I have bought all mine seperately and I have some from every brand. Not much experience with Bosch though. For cordless impacts snap on has had the top dog for a while, though I was looking at an Ingersoll that had better stats. The SO looks like it would be comfier though.
SnapOn makes a MEAN cordless impact! pricey but completely worth it.
IMHO it's Porter Cable hands down.Problem is though I'm quite sure ones built after 2004 or so might not be as good as earlier ones because Black + Decker own them. I bought a 4 pack combo 19.2 system that has been flawless.My sawzall has been to hell and back around my septics and drainage jobs cutting pipe and more,the percussion drill will twist your wrists if you allow it.As somebody else said,the smart battery choice is to have them rebuilt.A vendor in Texas does all mine,he's THE battery guy on Ebay,replaces the cells with better than OEM ones and cheaper than a new one.