From personal experience:
1. My male Red Devil- At 4-5 inches he was biting harder than my 7-8 inch male Texas cichlid ever did. The only fish in that size range to make me draw blood. At 7 inches he bit harder than my 9 inch male Jaguar cichlid, despite my male Jaguar having larger teeth. He’s around 9 inches now and he hasn’t bit me during water changes (yet) so I can’t judge his bite at that size.
2. My 9 inch male Jaguar Cichlid- He was pretty chill for the most part, did have a nasty little set of chompers though. The Parachromis family being piscivores, they don’t really have incredibly powerful jaws imo, the teeth (being meant to grasp fish) does most of the damage. Still powerful, just not as powerful as I expected it to be.
3. My 8-9 inch male Texas Cichlid- This guy was an anomaly

he was incredibly tolerant of other cichlids in my community tank but whenever I had to do water changes he went crazy. Made me bleed a couple times but his bites weren’t incredibly painful.
4. My 4 inch male Convict- bit me harder than I expected for a fish that size. Didn’t break skin or anything, just felt like a strong pinch.
5. My 13 inch female Oscar- her “bites” were more out of curiosity than aggression, kinda tickled more than anything lol.
Unranked:
My 12 inch female Buttikoferi- Didn’t make a mistake when putting my hand in her tank. I wasn’t gonna take that chance after hearing and seeing the damage their jaws in such a short amount of time, especially with her aggression level. I guarantee she would’ve taken 1st spot comfortably if she tagged me. I think when my Red Devil approached 12 inches he’ll be comfortable in that regard.
My male and female Jack Dempseys- both were really docile, shy fish. Never attempted to go after my hand.
If I had to make a list, I think Dovii and Umbees are up there due to size, then comes large cichlids like Buttikoferi, Trimacs, Chanchos, Midas, Red Devils, Jags, Black Nasties, Cubans, Istlanum, Grammodes, RTM’s etc. At equal sizes I think the Amphilophus family probably bites harder than the Parachromis family.