Several AdSense plugins fell by the wayside when WordPress changed the way that the editor pages worked. I think that was back in version 3.0 or 3.1. They removed some of the functions that plugin authors were using to add selections to the toolbar.
I am using a modified version of an obsolete plugin named Advertising Manager. The editor feature for inserting ads ceased functioning, but I found a workaround that fixed the problem. I am maintaining it myself and it still does what I want, but it may reach a point where it is no longer viable. An increasing number of WordPress plugins are being abandoned by authors because of the time it takes trying to maintain them with all of the structural changes the WordPress team keeps making. Too many plugins require code changes with every new leap from the WordPress team.
I would also like to find a new AdSense plugin for use with new sites. It needs to have the flexibility to place ads where ever I want to place them, and it needs to work from the editor pages.
"It's inexcusable for scientists to torture animals; let them make their experiments on journalists and politicians." -Henrik Ibsen