My fave mom: Leah for many of the reasons listed. She's had a lot of growth and really does the best for her kids. She makes questionable decisions sometimes (I cringe when Addie begins twerking and Leah thinks it's so cute) but that's a personal opinion. She's overcome drug addiction, coparents very well with Corey and Jeremy and generally does her best to stay away from drama and raise her kids.
I'd say Chelsea is my favorite but honestly, I feel like she went from one boy obsession to the other, and this one just happened to work out for her. She holds horrible grudges against Adam's family (maybe for good reason, idk) but she just hasn't really grown mentally from her teenage years. Also, that baby voice needs to go.
Least favorite is definitely Kailyn. I absolutely cannot stand Kailyn. I think I'd rather have Farrah on the show. Kailyn is extremely ignorant, mentally and emotionally abuses her ex's in various ways, causes issues with EVERYONE over nothing, has the biggest ego I've ever seen, pops out babies just to stay relevant, uses her platform to spew anti-vax nonsense, just drops anyone that she feels 'wronged' her and never looks back.
Fave dad is Corey. Idk why, but I've always had a soft spot for him. He just seems like a genuinely good person who loves with all his heart and cares about his family.
Least fave dad: David. Do I need a reason?