Cavalry are probably one of the most underestimated , under used thing in 8th edition.
But they do suffer from certain match ups where they will just die in droves. Such as Doom Diver/ Manglers
Under High Elves, I would say Dragon Princes is the only way to go , unless you are sticking 2 characters in there, then Silver Helms are just bodies to fill up space.
Dragon Princes are also nice vs the Flaming banner
2+ Save is always better than a 5+ right?
Step up Doesn't actually do much against them, It's just the steadfast, they are hardly ever going to break it unless its been severly thinned or infantry come in to 'Mop up'