Colour has nothing to do with temperament. The vital ingredient is upbringing. Socialise, and start training your puppy before he is sixteen weeks old using positive reinforcement, as opposed to negative reinforcement, and you will end up with a happy, well balanced dog.
I have had three solid Cockers and all have been fine. My present dog, Charley, is golden and you couldn't wish for a dog with a nicer nature. You can do anything to him and he won't growl or snap. Indeed, I don't know what you would have to do to get him to react badly. He's fine with other dogs and animals, and hasn't a bad bone in his body.