For cat stuff - definitly catnip! :D
Maybe pendant/artifact based
I like the idea of someone shaping your body like it's clay~

I'd say suits and goo but I'd really like to see more corruption based stuff, so weed and alcohol related stuff could worl great with that~

Definitely love weed and hypno!! For me though wishes and wishes going wrong are up there for me too!

The body changing to match the mind is definitely a good one! My favorite atm is probably affection based scenarios

For pokemon tfs is the pokeball

For werewolf tfs, it's either full moon or magic

For dragon tfs, magic

Possession is my fav tf trigger! I love the usually accompanying identity alteration/death.

Agree with you fs on weed/alc!!

Each species has it's own tf trigger. You could call it a pun logic.
Cat? Catnip.
Dog? Collar or treats. (Personally, also praise.)
Mouse? Cheese.
Dragon? Treasure.
Kobold? Dragon. (Use treasure to make the trigger, for bonus points.)

honestly all of these and sex

probably cursed items like masks, armor, etc

I love symbiotes personally! But another ool one I don't see a lot if magic tattoos

Fursuit/Mascot suits but specifically when they wear it long enough that it transforms them overtime! It's SOOO hard to find among the typical 'inanimate fursuit tfs' and the ones where the fursuit just becomes their body.. :(

Gotta say I love any clothing trigger, whether that be a collar, bandana, goggles etc. Just always fun, especially with hypno eyes after it

Weed and booze sound fun... as does any other substance that makes folks woozy and unpredictable or affects their personality. I can definitely see the parallels to hypno.

Bonus points if the trigger in question is very slow-acting and requires multiple doses or prolonged exposure to show any effects. I like the idea of a TFee deliberately going out of their way to achieve those changes - or, for a slightly darker take, being so obsessed with or addicted to the trigger in question that they barely have a choice in the matter.
Guess I like my sexy cute body horror with more than just a pinch of sexy cute psychological horror, as well. ^^

Not gonna lie though, picking favourites is hard, especially considering how fun it can be to stumble upon new and interesting takes!

I also really like when mental and physical transformations are combined! So I really enjoy hypnosis and mind alteration contributing to the changes! However, I also enjoy when it is a more subtle change in perspective rather than full hypnosis, such as gaining more confidence and happiness in the new body.

For specific triggers, my favorites probably include scents/musk, enchanted collars, drugs/aphrodisiacs, and massaging the body into a new form. But really any trigger can work well in the right context!

Well, it often depends on the theme, such as with:
Dog ---> Collar, Treat, Bone, Commands, etc
Rabbit ---> Carrots, Magic Tricks, Pocketwatches, etc.

But as my favourite TFs also include changes in personality, even up to complete Identity Death, I'd have to say that my favourite triggers are along the lines of hypnosis, corruption, and/or manipulation ^w^
It's so delightful to see someone go through the process of turning from a decent, average person, to a lunatic, creep, inhuman monster, or anything else of the like, with all the emotional pain being relieved by either their own choice to keep going or the forced desire/acceptance of the change >w<