Hermes beats flash hands down.
Even for users who don't have Pandora One, Hermes is and always will be a free application for everyone. If you'd like to donate, however, you are also welcome to.
Hermes pauses music when your computer sleeps, and it doesn't resume on wake. It fixes errors and picks up the song right where you left off.
You can like/dislike songs and create/edit/delete stations, just as on Pandora. Also, things like last.fm integration, and Growl notifications just aren't possible with Pandora.