Don't use plugin(s) for adsense, you can just edit your html/php code and add your adsense code there. many adsense plugin add there own ads to your site without asking..
It's easy for me to update the Php/HTML script, but it becomes a chore whenever a new version of the theme is released by the publisher. Once the theme is overwritten with the new version, the changes are gone. Hence, sometimes leveraging AdSense plugin is more convenient in the long-term basis.
That's better. But if you plan to use a plugin Quick Adsense is better, easy to use and lot of options. http://wordpress.org/plugins/quick-adsense/
I've used http://linewbie.com/wordpress-plugins/all-in-one-adsense-and-ypn for years, it has always worked good for me, I have tried others, but non are as good as this one. Though I've heard good things about premium adsense plugins too (you have to buy them), I haven't tried them.
All in one adsense and YPN plugin is the best free plugin available out there. I recommend it to all my blogger mates and they are very satisfied with it.
According to me Quick Adsense is better........ Here we go with the list of some Adsense plugin's.................. http://www.lunarpages.com/uptime/top-10-best-adsense-wordpress-plugins