i.. actually don't really like nicknames..
If we're talking about fictional pairings i like when sukuna calls megumi treasure or blessing, but i really dislike "meg" and "'gumi"
I also like when he calls Gojo "sorcerer" or "six eyes"
Blackmadhi might be an exception to my dislike of nicknames cause they're THE nicknames pairing

Outside of fiction, I do like "angel" (ange in my language) "dear" "love" (but not in french lol, way too cheesy), and probably others i can't remember rn !