Really depends on the tool and your use. My experience with the 18V impact driver is that it needs a top off every few hours, but that's a good time to take a break anyhow. However the Sawzall and chop saw will chew through the biggest batteries in minutes. Fortunately they charge quickly though they are rather expensive. I think they are on par with the Dewalt stuff though I like the Makita tools a bit more. I guess if my jobs were any bigger I'd be using pneumatic tools so I can deal with recharging between tasks.

I've been in plenty of job sites with limited power and heat, and a fresh cup of coffee would be much appreciated. Sometimes you can't make it down to the lunch truck!

DeWalt has really gone down hill. I recently switched to Milwaukee. I’m not a contractor but a have lots of friends who are, and they are almost all on Milwaukee these days.

Following from the sidelines I feel like there are similar comments made about all brands, both the "X has gone down hill" and "all my contractor friends use Y". I wouldn't put too much weight on such anecdotes.

I know this is anecdotal, but I would agree. I used to work in an auto shop, and we had lots od Dewalt drills & impact drivers. The older ones were typically fine after falling off a lift onto a concrete floor, but out of the new tools 2 drills and 1 impact driver were junk after the first fall. We just ended up buying adapters to use the new batteries with the old tools.

They're all 18650 cells at heart. Your Milwaukee Fuel drill and impact have brushless motors, probably with higher capacity batteries (measured in Amp-hours) than the Ryobi set, which have brushed motors and probably 1.5-2 Amp-hour batteries. There are plenty of power tool review blogs that do tests to see how many fasteners/board feet/etc different brands do with the same capacity battery packs.

FWIW, Milwaukee and Ryobi are owned by the same parent company, Techtronic Industries

I would be really surprised if there were any significant difference between the actual batteries between manufacturers. There isn't that much variation you can do with lithium cells. Biggest thing that comes to mind are the high/low level cutoffs, or how deep the protection circuitry allows charging/discharging. And that is fairly straightforward trade-off between how long the battery lasts on one charge vs how many charge-cycles it can take.