Tough call, probably Crysis 2 for consistency as much as anything. Metro starts building up a decent plot but has a tendancy to go a bit too leftfield and stuff (aka putting in some random 'cool ****') at times as there isn't sufficient suspension of disbelief to accept it.
I don't think either are particularly outstanding, it's a bit like asking whether people prefer white or brown bread, one may be better than the other but neither will really define your culinary tastes.