Shimano SPDs are easy to clip in and out of, reasonably priced and very durable. With mtn bike shoes, you are able to walk without cleat protectors. I've got some SPD pedals that are at least 10 years old and still working fine on one of my regular commuting bikes. They are available at several price points. I just bought some new PD-M540 pedals for about $50 with shipping.