I’m sure all of us are biased, so I’ll throw mine into the mix!
Leonberger. I’d definitely go for a bitch, slightly smaller in size. They have a really low propensity for barking (was a consideration of mine, am not a fan of dogs that constantly bark). Very low prey drive - important as I had cats.
They were bred as a companion dog, so don’t really have a “purpose” unlike sight hounds, gun dogs, pointers etc. I don’t have kids, but when I was working I had amazing doggy day are - my girl grew up with her kids in the 3 days a week I was at the office. She’s also always been great around other dogs no matter their size.
They look big, but they are actually really easy! I’d say my cats make their presence known more! I love big dogs like Newfies, but couldn’t handle the drool. Leo’s don’t drool.
Definitely regular brushing (they have double coats, so summer shedding is fun!).
Having been originally bred by crossing newfies and St Bernards, they are supposed to love water. Most of the ones I’ve met do. I’ve ended up with a weirdo who would rather walk round puddles! But lots of Leo owners do waterworks with their pets which they seem to really enjoy.