IMO, Time ATAC is the best system, but there is not a road version, hence LOOK (alikes) on my road bike.

Also too bad that Time ATAC mtn pedals have crappy bushing/bearings that wear out too dang quickly.

The ATAC cleat is captive on two rails; the spring rail is against the stop. It's simple, and secure. Clipin is auto.

The LOOK also has the sprung portion against the stop; it is simple and positive. The cleats and parts are easy to find.