I use Speedplay X pedals and I love them. LOVE them. I had bad knees from running and tried cycling for rehab. I'll never be a runner again, cycling is way more fun.

Anyway, the Speedplay X series have a lot of float, they're light, and they allow your stroke to follow it's natural pattern. As much as possible, anyway.

The downside is the huge cleats ... I clomp around like a Clydesdale, but the tradeoff is worth it.