Human Path has better PC options, which means its the preferable arc if you want to do the after game, where your options suddenly MATTER (granted, you ALWAYS get the super PC late in the after game, so that's one slot filled or something...if you get that far...). Main game is easy enough that such things aren't a big deal.
Fairy Path is...better at everything in terms of writing, really. Better characterization of Jack, the relationship with Ridley is actually well handled, Gawain is not as big a lamer since now his motives are clear, backstory is explained, and suddenly he MAKES SENSE, and Cross gets what's coming to him. Also has a few extra little fights and such with human characters that help show some emotional impact related to Jack's choice, rather than "Oh look, more elves, lets beat them up!" like the Human Path has.
(Granted, Zane, I think his name was, is hateful prick regardless which path you do. Nothing saves him, and I can't tell if you're suppose to hate him, or if the Fairy Path just failed to make you sympathize with him. Cross, the game very clearly wants you to be against him regardless, and both pathes do display him as a total dick)