Billy with the bromfields or vasquez's???
Hmm this is a tough one.
On the one hand the Bromfields have such an unusual dynamic with Billy that I think seeing them together is so interesting. There's a clash of lifestyles but they are all trying hard to be a family (in part for Mary's sake). Watching them grow together as a family is honestly an underutilized thing in fandom.
On the other hand, I think the Vasquezes are able to connect with Billy better because their life experiences are a lot closer to his. They are generally more involved with the kids' lives and and can roll with the craziness that comes with superhero life.
I think both have interesting and underutilized dynamics with Billy. Maybe it's a cop out, but I feel like it really depends on the story you want to read/write and the lore you're more comfortable with. I prefer Billy and Mary being twins but I've written Billy and the Vasquezes more often.
I tend to write Billy's life prior to becoming a part of these families because I never know which to pick so maybe I'm just indecisive.