The border collie is not a good choice for someone who is at work all day. The dog is high energy, like you have been told, and will most likely end up with behavioral problems.
Most of the blue merles are also herding breeds (like Aussies, Koolies, Catahoula hounds, and corgis.) None of them are suitable dogs when left alone all day. The one merle dog that you should look into is the Great Dane. They are very large, so I do not know if you want one, but they are good apartment dogs and can sometimes do well when left alone. (It depends very much on the individual.)