Mocap only looks good for smaller, more "believable" movements. The emotes in this game, for example, are wonderful because of the mocap. It also runs in line with L.A. Noire looking fine with it. Also makes more sense when the characters look realistic. When the characters are very stylized it tends to look creepy.

Regular Animation looks best for stuff like flips and high jumps and things that people obviously can't do IRL, as well as more fantasy-ish characters/races.

IIRC I think the devs actually use a combination of both. In the Making of FF14 video it was mentioned that they tweak the mocap for animations so they fit the different races better.