I've only used SPD's, so I can't comment, but there are a lot of dedicated followers of all different pedal/cleat combos. On the face of it, the Speedplays have the float factor going for them, but are smaller platform - however many people maintain that size is a red herring for them relative to hotspots.

As far as I know, they all have tension adjustments that can change the clip-ability factor.

It's a good question -- although I'm content with my pedals, I'd like to try some others just to see what they're like...