The realm first Hardmode titles done while current content. Naxx, Maly and OS realm first titles mean nothing at all imo. Also Herald of the Titans and the Immortal done while current content are quite impressive to me. I am aware you still need to be 80 and so on for Herald but it's nowhere near as challenging as it once was thanks to how high dps and health pools have scaled at 80.
The immortal and the undying became fairly faceroll with gear too. There was some RNG but overall it wasn't too bad. Failed it twice due to stupidity with people running late behind iceblocks on Sapph.