I'm running Dungeon World right now and enjoy it a lot. It's not perfect, but it's fast and easy to get new players into the action (I have two players who have never touched an RPG before).
Spire is easily the most flavorful read I've encountered in years, and it's next on my list to run.
Nobilis 2nd edition is the game that spoke to my soul and convinced me to start designing "professionally".
Might I humbly suggest my own games? A bunch of them are free, and all of them are cheap.