Pleasantly surprised by all the love for Li Xiu!
But I agree, I wouldl pick Li over Chao as she has more general utility. I have Li and Chao both, Li gets used on both Raid/War defense and offense; but I only use Chao on offense, and often stacked with Li anyway.
Li is by far the better defender.
On offense, Chao has slight edge (charges faster, and thus better to slow down a particularly nasty enemy hero); but Li is still very useful as she slows down ALL heroes - especially really helpful when I don’t bring Proteus, or when I accidentally trigger a gem cascade that hits everyone…
One more drawback is when riposte is active; I can safely use Chao against one of the enemy heroes not covered by riposte, but Li will end up taking a bit of damage if I use her skill.