I know the negative stigma around the third movie, but I personally enjoy it a lot, even to this day, as bad as it probably is in actuality. That said, I never had an issue with Eric. Always thought he was smart. Kind of had to be to survive as long as he did on an island inhabited by giant, ancient predators.
Also didn’t mind Zach and Gray, as much as the older brother (can’t remember which one that was off the top of my head) was a jerk at the beginning. He pulled through for his little bro halfway through the movie, which is exactly how my family works. We get on each other’s nerves a lot, but if you mess with one of us, expect a LOT of trouble.
As for a WORST kid, I guess Maisie. She doesn’t really do much throughout the movie aside from run, hide, and then let all the dinos free at the end. Not saying I disliked her, just that she easily did the LEAST in terms of protecting not just her self, but anyone aside from the dinos.