Always leave it on...have to know if it gets down too low. I can't imagine not having it on.
Nope, I leave it off. If I see the number there I find myself checking it all the time; when it's off I don't even think about battery life most of the time.
Lol, I used to always have my percentage on, but then I turned it off and realized I don't check my percentage, but am still aware of when I need to charge because the color of the battery changes.
The exception is I do leave it on when I get a new device, only so I can monitor it's drainage. Once I get how it drains, I turn off the percentage.