I've had 3 labs. 2 yellow males and one black female. Labs do have different levels of intelligence as to what color is the most intelligent that's a great question that i'm not sure how to answer. But will share this with you: I've spent several years working with a Field Trial trainer who handled many dogs at one time. I also have a neighbor now who trains labs or should I say, trained labs. It all depends on what you are trying to accomplish with your dog but if you are looking for a solid hunting dog that retrieves single, doubles, triples, and blinds, then the best kind I've seen is a black female. Now, this female needs to come from a bloodline that has a solid line of proven hunt test/field trial dogs. Secondly, you need to really pay attention to how that puppy responds to a thrown object (like a small sock with some paper in it, we call it a small "bumper"). What I've observed is even at 6-8 weeks old the more solid puppies will pay attention and even go after that thrown "bumper". Even knowing all of this, you still have the risk of the dog not performing the way you imagined. Like gun shy or doesn't like to retrieve certain birds or water situations. They are after all dogs. If you really want to bypass some heavy training then look for a dog who is already past some of those initial stages. Find a breeder who has a 8-12 month lab that has already started basic hunt trials or field trial testing. They should be completely through their basic obedience work by that age.
If you are looking for a family have fun dog, you still want to watch the bloodline, some of these bloodlines are little to close and the dogs get a little out of control. Ask the owners about the parents of the dog, see how they were are as young dogs, questions like this will help you pick a better puppy.
I know this long but hope it helps!
By the way, my black female dog was 100% better dog than the two yellow males. I still loved them all but she was a machine at work when it came to retrieving, and an absolute family dog when we got home.