What is it?
For me it’s the Blazing Drake. I’ve been farming for this damn thing since half of Legion, and all of BfA. It’s the last drake mount i need for the Awake the Drakes achievement. I’ve gotten 3 Lifebinder’s Handmaidens, and 2 Experiment-12B’s, but not a single Blazing Drake. 
Hope you guys have better luck than me for whatever it is you’re after.
I got 3 experiment 12b’s in one day one time when i was farming that. Ended up taking me about 4 years to get it. Keep at it! Emerald drake is worth it, any mount collector worth their salt will respect seeing you riding around on that! 
For me right now, it is mount related too. Sha of anger mount.
Not on my mage, but my priest. I’ve been trying to farm the shards to Val’anyr, Hammer of Ancient Kings but the blasted things just will not drop outside of the 1 I get from Yogg-Saron every week.
It’s been about 14 weeks now and it’s getting frustrating.
Ashes of Alar. I’ve about given up. It seems like everyone but me has it.
Back in the day it was Skull of Gul’dan. Only ever saw it twice. First time it went to one of our mages, no problem. Second time it went to a trial, who left the guild two weeks later. I was a little salty about the latter.
Everything I’ve actively farmed for has dropped…
Except Heavenly Onyx.
But I never expect that to drop anyway. I just tell myself that The Sha of Anger stole my lunch money as a wee little night elf, I’m going to eternally repay him back by using him as a punching bag multiple times a week across all my alts.
Mine has to be the HH mount. Sure the graphics are dated but it’s still eluding me.
Since it came out, that was the one mount I have farmed the 2 weeks on multiple toons to still come up nada. I have farmed and received many other mounts but that one I covet most of all. Now its a matter of being stubborn and the principal of it all. 
H
Well…it was the Tomb Stalker from King’s Rest, I ran it exactly 380 times to aquire that mount. (M+ and M0 combined) The mount that is currently elluding me, well, 2 actually, the jelly fish from argus (I think i have over 15,000 casts, absolutely ridiculous tbh) and G.M.O.D, of which I have over 100 Might of the Alliance / Victory or Death runs (Jaina kills), in LFR.
Same here!
I gave up on farming it though.
That raid is just the worst.
Galleon. 5+ years, 3000+ kills… 21 alt army hitting it every week.
Crimson Felt Hat. Been trying for 15 years. It will never drop for me.
Ugh, agreed. I hate it so much. I cant stop farming though, not when i’m so close.
Still need the Hippo from the court paragon chest, I am tired of going to legion land Blizz!
It was my favourite one so of course it’s my last to capture, hah.
If only that’s how it really worked 
The Warden Paragon Chest toy.
I’ve been farming it since it was possible to start farming it.
No luck so far.
I’m pretty sure Al’ar was easier to get…
I meant so close to finishing the Awake the Drakes achievement.
I was confused for a second there. And then i realized you were talking about the Hippogryph, and not an actual Hippo lol.
5 alts running LFR/Normal/Heroic/Mythic Antorus, I’ve looted every non-tier piece from Normal and Heroic, I’ve gotten both the Blue and Red Scythe of the Unmaker, 231 Kills recorded and summed up.
I. Just. Want. TAESHALACH.
All 3 drakes from dragon soul 
I have the Red Scythe from Argus and the 2h sword from the other dude . The scythe is so evil I love it! I use it on my paladin/dk mostly.
Anyways, good luck! both are some of the best xmogs IMO.
