Hmm... I guess mine would be niacinamide (as I stare at my Holy Snail's Whale Shark and have a Geek & Gorgeous B-Bomb on the way 😅). Like, it's nice, but at the same time I really don't feel like this ingredient does much for me. I keep using it because it doesn't hurt me, but I'm not sure if it's just placebo at this point lol