My favorite kink is (and likely always will be) hypnosis/mind control. There are so many different flavors and combinations with other kinks that make it rewarding to revisit over and over again. It's a beautiful framing device in fiction for giving a character a chance to let go of things holding them back from enjoying a pleasure they want deep down, but can't acknowledge for whatever reason. And even if the character doesn't want it, the reader will, and it gives them a chance to project their desires onto the character. From a more dominant perspective, it's thrilling to watch someone obey your commands and feel true pleasure solely from your actions and words. The exchange of power is crystal clear, in-your-face, on display and extremely sexy. And the cherry on top is when a big strong fella ends up totally compromised, with his physical strength repurposed to serve another's will.

Honorable mentions:
Corruption - I can make him worse (and therefore better/hotter)

Chest Fixations - Sexualizing a body part usually for displaying virility and strength. Nipple piercings, pec growth, milking, all wonderful to do to a chest.

Brainwashing/Identity Rewriting - A powerful flavor of hypno/MC that hits VERY nicely.

Vore - A relatively newer discovery that finally started clicking for me. Chest and Cock Vore are my favorites. Being enveloped and incorporated into a superior being physically isn't that far from hypno.

Transformation - Brutification, Himbofication, Species, Gender, etc. All fall under this umbrella for me. Very appealing if the person transforming is pulled into a new mental state and finds it seductively fulfilling, especially if there's an internal monlogue about how conflicted they feel on the pleasure of the new form.

Sexy Betrayal - Specifically for horny fiction, when a member of a team or adventuring party is compromised and ultimately leads the rest of the group down the same path toward serving a dominant's will.