I still love my old ZG tiger - mainly because I remember farming that for soooo long.

purple skeletal warhorse

Heavenly Onyx was BMAH (scouted lower pop servers, and xfered a guild bank in hopes I wouldn't be out-bid, paid 2.2 mill) but I farmed off and on since MOP across various characters and servers.

Zulian Tiger was BMAH as well when goldcap was 1mill... also server xfered for that one lol...Razashi Raptor was a drop and constant reminder for years that I would "never" get the tiger, but that changed in WOD for me (:

spectral wind rider

Phosphorescent Stone Drake. I haven't played in years so I don't even know if it's that rare anymore

scarab lord