The Prisoner has a lot of good options because of his Special scaling... you can really get yourself a well-defended unit using gunner talis without sacrificing all of your offensive potential.

Primordials are fine, though I've always found them a bit pedestrian.

Vanhala/Light + a nice cosmic seems like a good fit.

Sacred/Immunity are both (well, maybe not Sacred) underrated 2-sets. You could pair either with Serenity/Angel to get a unit that is very well defended and hard to slow down.

Radiant seems like a good way to kick a fellow while he's down.. and although I'm less fond of 4-sets in the wake of Cosmic Talis (which can be 4-sets themselves, now, giving you essentially three extra slots), perhaps my favorite 4/2 combo to slot a Yellows unit with has to be Sacred/Banner. Your opponent has no good options facing that set (well... unless you're heal-blocked or craved), especially if they're hitting with area damage.

I don't own Riders. They seem good.