Transformation, or some otherwise form of shape shifting, but it's pretty finicky. For instance, while I'm indifferent towards either thin or fat women, the process of them gaining/losing weight is a huge turn on. If it's gaining, I don't like a slovenly lifestyle, and once it's difficult to notice small changes (~350 lbs), the pleasure turns to concern for their health. Thankfully the kink works in both directions!
Because weight gain carries very real risks in life, I often actually prefer seeing it animated. It's gotten to the point where I'm a walking encyclopedia of artists in the field. There's a user here who once had a fat Cortana avatar, and I could instantly name the artist and stage of the sequence. If it's expansion art, especially a sequence- I've probably seen it.
Staying within the realm of drawings lets my transformation kink kick up a bit too. I'm not into furries or werewolves, but seeing women transform into bees, nagas, squids, etc, is awesome. Provided they stay at least somewhat humanoid; a straight-up tiny bee would be going too far. Once I saw an image set of a woman being forced on a phoenix egg, whereupon she slowly started sprouting feathers and talons. Eventually she pleasured herself with it as she turned into a full hybrid, and it was one of the sexiest things I'd ever seen. There was another one where a drider unbirthed a human victim into a hatchling, but I I prefer the process to at least have a hint of consent at some point.
I used to think I had a corruption fetish too, and while I think the idea can be fun sometimes, I definitely like redemption better. It's a shame though, while good->bad content is easy to find, it's next to impossible to find the opposite. I remember once reading a long story about a man traveling with a captured succubus as they worked to turn her human again. Seeing her mindless hostility slowly turn to frustration and snark, then to genuine kindness was just off the whazoo. When it described her finally smiling again...;-; Like I said though, that stuff is rare, so thank you Fire Emblem for giving me Aversa!
Ornate or unorthodox hairstyles too. If you can get creative with the way you style your hair, that is hot. Hair loopies or front braids, to name a couple.
