For me, the choice was tough, but I ultimately decided to go simple yet obscure. In the Animated Series, Batman had two major types of Batarang--the classic version, and ones that appeared to be razor-sharp, and shaped more like shuriken:
The DCAU wiki calls these "Bat Stars," which is as good a name as any. I've always really liked the look of them, and they're a nice alternative to the more traditional Batarang.
So what's your favorite bat-gadget?