I used M-520s for quite a while and liked them. They're highly adjustable, reliable, easy to maintain, and do allow you to wear shoes with recessed cleats. They have clips on both sides so they don't have a platform side, but if your non-biking shoes are stiff-soled (e.g., hiking boots) you can do it for a short while no problem.

I also tried the ones with a platform on one side and a clip on the other (A-530?) and I hated them. The side with the clip is heavier than the platform side, so if you want to ride with clips, you're constantly having to flip the pedal over with your toe before you can clip in. For me, it was almost as annoying as using old-fashioned toe clips. If you mostly like to ride while clipped in, it's probably more convenient to just go with pedals that have clips on two sides.