
The best person to advise as to the best dog for your individual bitch is her breeder (if reputable).
First of all she'll need to be KC registered, the right age, and satisfactorily hip-scored and eye-tested, and preferably elbow-scored too, as well as independently assessed as a good example of the breed (we all think our animals are the best!). Of course this applies to the stud dog too! Also you'll need to study her pedigree and that of any potential stud (this is where a knowledgeable breeder's help is invaluable) to make sure you're not doubling up on faults.
There were 45,000 labrador puppies registered with the KC last year, and probably about as many again unregistered or with 'the other' registry, so the competition to find the good homes is very fierce - you'll need to be able to prove your litter's absolutely top-flight ... It's almost guaranteed that the most suitable stud - and he has to be chosen very carefully, because you want to produce quality, not mediocre, puppies, as they're 10-a-penny - will be over 100 miles away ...