My recommendation would be Ryobi cordless. They all use the same battery and they have been very reliable for me. I understand people recommending Bosch and Milwaukee and Makita and Dewalt, and they are all very good. Ryobi is relatively inexpensive and very easy to find (Home Depot) and has tons of tools that all run on the same battery. I used the angle grinder yesterday to cut up some metal, the impact driver is the best (relax guys, I am not saying it is the best made, I am saying it is comfortable and strong and reliable), the drill is also very good, the hammer drill amazed me at how much work it could do on one battery installing windows with tapcons. The circular saw is also fairly long lasting on a full charged lithium battery. Sawzall works fine. You could do a lot worse.
For what it is worth, unless you are homeless under a bridge, I would steer away from the Harbor Freight cordless tools. Yes, they are cheap, and I used to buy the drills, but the tools aren't as comfortable to use and batteries do not play as nicely together as I would prefer. At least when I was using them.
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