Sometimes a carefully-bred puppy from a responsible, thoughtful breeder is what fits your household and lifestyle best. There's no shame in that.
I've had both rescue dogs and those we had from puppies. The rescues have both meant going back and fixing other people's mistakes. One is an ex-breeding girl from a puppy farm. Her first four to six years were absolutely horrendous. She was deprived of all normal dog activities - going outside, sniffing things, going for a walk, kindness and gentleness from humans. We've had her for coming on seven years and had to realise that she is not, and never will be, a "normal" dog. Her early life scarred her too greatly. She's elderly and coming to the end of her life, and she's enjoyed what we've given her - good food, canine companionship, a warm bed, people and dogs to snuggle up to, walks and exciting things to sniff. But it's taken a lot of time, she requires a lot of support from the people and dogs that she trusts, and there are situations that she can't handle without shutting down.
My sister's dog was placed in a rescue at the age of six months because the owners couldn't cope with a small baby, the husband on deployment and a young male springer spaniel. He's a lovely boy but needed work with a behaviourist to establish boundaries and work on jealousy issues. He's settled down a lot but was definitely a bit of a project to start with!
Given that you have other dogs with interesting backgrounds, a puppy will probably be more adaptable and you can socialise and train them exactly as you wish.
It's so important to support the good, responsible breeders who are careful about health testing, know their lines and avoid inbreeding, and who gives their dogs a solid foundation that will set them up nicely for the rest of their lives. It sounds like you've found one and I hope you find your next companion from them. Personally I think bi blues are stunning but alas, my wife doesn't like dogs so it will have to remain a dream for me.
