I was thinking about my current homebrew …
I run my own version of Greyhawk for 24 years, and I exclude certain monsters, my take on those you mention:
Dragonborn - Agree, I have never used them and probably never will.
I don’t like half-dragons or half-fiends either. The feel is weird to me of sort of draconic, mostly humanoid. There is an adventure with a Dungeon adventure with half-dragon I want to run someday, but it’s really good and about a unique half-dragon and his dragon father, not “3 Dragonborn sorcerers are in Room 3” stuff, accepting it as mundane.
I like an use often Lizardmen, and have no problem with Tielfings or AasImar if the story supports (again, not no personality ones with no background - would be an exception with a reason).
Lycanthropes - I rarely use them, but I have no problem with them. In general, I like D&D with roots in mythology or at least outside self-referential D&D (see not liking Dragonborn).
Tritons - I agree there are too many watery humanoids. In general, I avoid aquatic adventures - as the Ten Foot Pool reviewer has said, many of them are just bad. The last I ran was U123 Saltmarsh series (in AD&D 1e) around 1996 and enjoyed it, but haven’t had a desire for more. For a good adventure, I would do it. I have zero attachment to Tritons. Sahuagin or aquatic elves or locathah or selkie I’d use first.
Githyanki & Githzerai - I find the adventures they are, generally are bad. Self-referential D&D overdrive. But when a PC used Dismissal to send an NPC home from the Temple of Elemental Evil’s Nodes, I told the story (when they checked in via Sending), that he accidentally went to a CN outer plane, met up with Gith and traveled with them to the Prime - but he is Faerun now, not Greyhawk, oops.
Giralon - I have used them. To me, like Owlbears - the “Good” stuff of self-referential D&D, which generally means it doesn’t hit an “over the top“ feel and is a monster, not a PC option/somebody you’ll meet at a cantina, I guess.
Djinni & Efreeti - I haven’t used them that I can recall, but they fit what I like - mythology that doesn’t come from gonzo game writing, but an older tradition.