Set it and forget it
Once you set up AdSense it's maintenance-free, as I found on my site at http://www.eTIP.ca. Just set it and forget it.
I'm not saying that you won't spend oodles of time tweaking your site to maximize your AdSense revenue, but that's up to you.
The truth is you can set up a multitude of sites using templates with the AdSense code embedded in them, and let the income roll in. (At least, that's what the guys who sell these templates say.)
The point is that adding AdSense to your site does not require ongoing maintenance.
So the third criterion for an AdSense alternative is that it must be maintenance-free.
Don
p.s. Still testing SearchFeed, which is also maintenance-free.