I have the battery powered four-gallon Ryobi battery powered backpack sprayer love it.
I usually walk around with it for a leg workout. I should just put it on the cart make it easier.
I have the manual 4 gallon and use it most of the time. The driveway is over 1/4 mile and I have to fill it several times and only one water source near the house, so much more efficient with the larger capacity.