I have two favorites, Ridgid and Milwaukee M12. After years of frustrations with Ryobi batteries, I switched to a starter set of Ridgid 18-volt tools on sale at the Home Depot back in 2012. The LSA (lifetime service agreement) got me since it covered the batteries. Since the initial Ridgid purchase, the Ridgid tool collection has grown.
I got into the Milwaukee M12 line when I needed a ratchet. Since then my M12 line of tools has grown. The M12s offer a balance between power and size, I don't always need 1,500 pounds of nut-busting or a 7" circular saw. The M12 line offered up some nice tools like a portable vacuum, soldering iron, stabler, and my new favorite, a sprayer.
I don't think there is a bad brand of cordless tools, there are commercial-quality and homeowner-quality brands. The anchor point is the batteries. Once you get into a cordless brand, you build an expensive collection of batteries that keeps you in the same tool brand. All you can hope for is the brand you have will keep offering up new tools and provide the tools you are looking for.