Also be aware that many pedal makers use one of the three popular drilling patterns for cleats that are not compatible with the originator of that pattern. For example, Campagnolo's Pro-Fit cleats fit the Look drilling pattern, but are not interchangeable with Look cleats when you try to clip into the pedal. Likewise with the numerous variations on SPDs. Some cleats may require you carve away bits of the sole to get adequate clearance for the pedal. Many road shoes are pre-drilled for SPD and Look.
Some people claim that pedal size affects foot comfort with clipless systems, larger being better.
FWIW, I currently ride on Bebop pedals. I like them. When I tour alone, I simply pray that the rear tyre won't go flat. One of these days, my luck will undoubtedly run out. Standardization would help, as well as information about tools that would reach wherever the connections are and provide room for proper torque.