Vote: ClearStream 2

Why: It's about as powerful as indoor antennas come. It isn't the prettiest (honestly, I'd barely call it "indoor"—though it does work really well indoors), but it gets the job done better than any other antenna I've used.

Obviously, as we've said, which antenna you choose has a lot to do with your location and what channels you need. The big advantage of the ClearStream 2 over something like the Mohu or HD Frequency is that it's directional. That means it's more powerful, but only in one direction—so if your stations are all in the same direction relative to your location (all my local stations are located due northwest from me), it's the most reliable way to get them. If they're all around you, you might be better off with the others.