[PvK]

They're all good but not game winners by themselves, and tend to be on the light side in terms of Protection.

Jade have the lightest cavalry, but it is dirt cheap (40 gold and sacred). The Onyx cavalry is definitely unique - huge fatigue but with a Fear effect. Like the Gryphon Riders, the I expect the Onyx cavalry is better, the more you have - neither would do well in a heavy head-on battle with very tough and brave opponents, but enough of them can annihilate a less formidable target.

Crystal amazons have air and astral magic and accuracy 13 + Air, they all carry short bows and their cavalry ride pegasi. They are a lot cheaper than gryphon riders (50 gold and 5 resources) and are much more fragile (and I don't think the pegasus stays to fight after the rider falls, at all), but they do have 18 defense... combine that with a heavy water blessing and they might never get hit. Their melee attacks are just Light Lance and Hoof, though.

PvK