I've been running Milwaukee M18 cordless for about 10 years now and have no regrets. Had Bosch 14.4 ni-cad before that. Upgraded gradually, and having two different battery platforms in the van was a minor but constant pain in the butt for me.
There are cheaper tools, but I've only regretted spending the extra for Milwaukee at the time of purchase. The regret that comes with buying a cheap version of a tool that you use regularly lasts a long time.
The Milwaukee batteries are amazing. I think that's where a lot of cheaper brands save a few bucks, and it shows in tools that are used daily.