I've tried to minimize the number of battery families I have, but I did buy into the Ego set of tools ~10 years ago for the yard tools, starting with the mower but I've since added the trimmer and chainsaw. Not having to do small motor repair and maintenance has been so nice!

I was a little annoyed that some of the Milwaukee tools require you to go with the M12 battery (the "bandfile" is what sucked me in) so now I've got 2 battery ecosystems for the tools, but I guess that's not the end of the world.