man, that's a can o' bees you're going to open there. people get real worked up about their choice of pedal systems.

my first piece of advice is to do some searchin' around this forum and that mtb review site and try and think about what features are important to you (easy clip in, price, "mud shedding" (whatever the heck that is), float, availability of replacement parts &c.) then choose your pedal system and ignore what everyone else has to say.

my second piece of advice is to get egg beaters -- if you don't you're skinny-panted hipster!

ignore my second piece of advice.