I had craftsman 18v stuff from many years back. I rebuilt the batteries once, and the second time they died, I started buying Dewalt 18v. It is expensive, no doubt, but it is worth the money. I started with a hammerdrill, then added a sawzall, then impact and a light, then the saw, finally added the radio and vacuum. A number of mine I bought as "tool only", because you only need so many batteries. A number of them I also bought as "refurbished" from Amazon. All of them have given me no trouble. I have both Lithium-Ion batteries, and XRP batteries. The XRP seem to give a bit longer run time, but they make the tools much heavier. A couple months ago I drove over 1000 2.5" screws into a deck in a period of 6 hours. The drill kept up, and the battery chargers could charge the batteries faster than I could use them.
One thing to watch out for, is that the kits are a great value, but don't always have the top tools in them. For example, a lot of the kits come with the small impact, where I wanted the large one.
I also recently purchased the 12 volt li-ion drill, impact, and halogen light. All of them are excellent, and have quite a bit of power. Not the level of 18 volt, but enough for simple around the house stuff.
I bought Dewalt due to the reviews, wide variety of tools, the professionals I have worked with all love their Dewalt, and I like that they haven't changed their battery in 15 years. With that said, their 20 volt li-ion stuff has just come out, and looks really nice, but also really pricey.
I hear a number of people say "I prefer corded", which is of course cheaper, and removes the hassle of batteries. With modern cordless, the tools are so powerful, that I don't think going cordless is a compromise. Maybe with the circular saw, it is a bit of a compromise, but I find the cordless stuff greatly drops my frustration level, because I can quickly move the tools where I want. It is very frustrating to be trying to rip an 8 ft piece of plywood with a saw that has a 6 ft cord, and having the plug get caught on the end of the board.