@PollyRoulllson speaks a lot of sense in her post upthread. A lot of posters have come down way too hard on OP. It just serves to put off other people who might later post here for advice: who wants to get bollocked for wanting a puppy?
And in all honesty yes, puppies are very hard work, some much more so than others. But even our worst puppy wasn't as difficult and demanding as any of our babies. And by 18 months most dogs are fairly civilised. By 3, even the most late-maturing breed is really quite grown up and nice to know. Whereas human 3-yr-olds....
OP, I will echo what others say: think about the breeds and their needs and how they'd fit in with your life. A good fit? Go and meet some. A bad fit? Think again.
As for breeders... Proper minefield. You can find decent breeders in Pets4Homes, but you need to do a LOT of due diligence. I have a very lovely dog who we found on there; her breeder home-checked all his buyers, has used his sense with regard to the stud, was happy for us to make repeated visits and so on (he's kept in touch). And you need to think what matters most to you. I'd rather have a puppy with a low co-efficient of inbreeding (COI), no health tests and and a dam in work at 5 and a sire still in work at 10, than one with a high COI, loads of health tests, and both parents very young and untried in any activity (agility, obedience, whatever work the breed was designed to do).
And not rescues, and not all rescue dogs, are equal. There is someone near us who wanted one dog to be a happy house pet and the rescue convinced them to take a pair who have multiple issues and cannot be off-lead. this wasn't their plan for dog ownership, but they're stuck for about a decade. Someone else acquired a failed gundog direct from the breeder/trainer, young adult, trained, wonderful disposition, just not cut out for the work, and they couldn't be happier.
Keep an open mind, talk to experienced dog owners in the park or wherever, and good luck.