Title.
If you dont want to discuss non-issues and minor nitpicks this one isnt for you.
Feel this so noticeable next to Evokers and Paladins who also use our holy magic in their abilities.
Disc priests and holy priests have few cool abilities. And since cool is a subjective term, I am referring to abilities where the spell looks cinematic, flashy and powerful looking. Disc priest offensive abilities only feature a few actual projectile attacks penance, PW:Sol, lights wrath and star/halo. Smite, PtW, mindgames, mind blast are all tiny little blobs that appear on the target.
Shadow priests are better, many can agree they look OK, but still have half their kit being visually unimpressive DoTs. They do however have shadowy apparitions and shadow crash and tendrily goodness, so they aren't terrible but still behind other casters.
Of the entire priests holy abilities kit, only penance and halo look like a powerful spell channeling holy light.