Hmm... Gavilar probably wasn't a religious zealot, he just used the Sons of Honor's zealotry to manipulate them. It's possible that the organization started out that way though. He only saw his children in terms of how they reflected on him, so yeah, he's the worst.
Uh... what? Elhokar was willing to execute Kaladin for besmirching a Lighteyes by accusing them of crime. He was embarrassed by his and Roshone's imprisonment of Moash's grandparents and basically waited for them to die in there. So nope on that front. The better Elhokar we see is from the influence of the rest of the family. I doubt Gavilar paid much attention to his children, given their distant PR-approved impression of him.
Dalinar basically wasn't even a father to his children when they were young and was almost always away on war. He showed blatant favouritism towards Adolin because of Renarin's sickness. He was influenced by an Unmade and wasn't mentally sound, so that's something. He does care but he's very overbearing.
Lin Davar and the rest of the Davar family was also influenced by an Unmade:
There's still a lot to uncover from Shallan's past. But yeah, Lin was very physically abusive towards his sons, that one alone elevates him on the rankings of bad dad. Kind of tried to make Shallan feel whenever he beat his new wife, sons or staff, it was her fault. Though he apparently tried to take the blame for Shallan killing her mother, so he might've been a good person once, deep inside.
Lirin is... good god, he's the Asian parent meme extreme. "You doctor now", and oh hey, Kaladin was actually pre-pubescent when he became a surgeon, congrats Lirin! Joking aside, he might as well have been singing "mother knows best", I mean "father knows best" to Rapunzel, I mean Kaladin throughout RoW without as much as pretending to consider Kaladin's side or mental state. He was very obtuse and obstinate.
So 1st place goes to Gavilar
2nd place goes to Lin Davar
Lirin and Dalinar are tied for 3rd place