Eggbeaters have a reputation for breaking within a few years, whereas all the other pedal systems last much, much longer. To be fair they did come out with new versions last year, don't know if they actually improved reliability.

Shimano spd's are good cleats, they don't have a lot of "float" but they're reliable, good, cheap, etc.

Time ATAC's are my favorite "mountain" cleat/pedal. They have more float than spd's (though a few people prefer the more restricted float of spd's), better at shedding ice/snow/mud (I bike in the winter), and like spd's they have a reputation for lasting a long time.

However, those are all mountain cleats.

As other people have said, with a shoe with a stiff sole their isn't any difference in power transfer between mountain and road shoes.

I ride with Speedplay Light Action's on my longer distance road bike. I like them because they're dual-sided so I don't have to look down to clip one foot back in, and they have a ton of float. If I had to buy new stuff though, I'm not sure whether I would stick with Time ATAC's on all my bikes, or still go with Speedplays on my long distance road bike. I dunno...there's not a "huge" difference.