Always wondered if there was any practical difference in those. I always go with lever lever traps to use the cord somewhere else - but have you noticed better efficacy somehow?
In light levers, I caught birds, hares, squirrels, ermines and even a small fox once. The few times I've tried loops, I felt it worked equally.
There is the little matter of a new 3.5b2 spell that should make snares more appealing to hares.. maybe it doesn't work with light lever traps?
(same as fox trap vs other traps for foxes.. there's a spell that mentions the former but I don't know if works on light lever or deadfalls too)