I've been with the SPDs for years. They work with mountain shoes, as well as sandals, and they shed mud well--a plus for the more adventuresome rider. Now I use the touring model (Shimano PD-A520). They are one-sided, but they hang with the catches toward the rider, which is particularly helpful for the 'bent rider.
I much prefer Sidi for my shoes, as the fit is reliable, and the shoes are durable. They are expensive, however. I buy mine on closeout sales, so I'm not fashionable, but I keep more money. Heck! I wear mountain bike shoes on my road bike, so who needs fashion?!!