I use Milwaukee M18 tools professionally and can tell you their Lion batteries are some of the best. I've had used, new, several capacities and have yet to have a battery die in over 5 years of daily use. Now, I do wonder if constant use, many charge and discharge cycles is better for a battery than a homeowner who uses a battery occasionally. I dunno? The new Lion batteries are the best I've ever used and almost any of the top manufacturers make really good batteries. I also use Makita 12v tools and they too hold up really well. My son the contractor uses mostly Rigid and Dewalt and he seems to have no real problem with batteries, and he uses far, far more cordless tools than I ever do and I use a lot.