Pull down,
Pull back
Pull over

Therefore total development should include movements from all three groups.
During the heyday of Gold’s Gym the philosophy was overhead pulling, horizontal pulling and pulling from the ground. The pullover was use a transitional movement between chest and back work.
Using points on the spine and thinking a bit three dimensionally, we can track the movements that all these back development articles talk about. Let’s start with the the seventh cervical vertabrae, on the base of the neck. If that is the axis, the shoulders can be moved BACK from this plane, pinching together the shoulder blades in kind of a backward shrug. While maintaining this image in your mind, think of drawing the shoulder girdle DOWN. This would shorten the distance between you shoulders and hips. The last component involves associated muscle groups, and that would be shortening the distance between your seventh cervical vertabrae and your tailbone. This reduces laxity in the back and increases total tension.

So you ask, "What about the PULLOVER? A pullover actually pulls the shoulder girdle down and back. It also starts in a pre-stretched position. The limiting factor, of course is the triceps limiting the both the amount of weight and the duration of the exercise. Arthur Jones solved this issue by apply the force directly to the upper arm. Many trainee’s don’t like machines or feel that they were injured by them. Most of those trainees were just poorly instructed and didn’t use the tool properly. The pullover machine is a powerful tool for lat growth. It is not however without shortcomings. You would have to be wedged in back AND front to apply force through the great range of motion. Remember, the machine originally had a 260 degree range of motion around the shoulder joint. It was increased to 290 degrees. I have personally trained several individuals who could exceed this. The huge range of variability in size and flexibility of individuals make this an exercise that must be supported by good instruction. Many free weight exercises don’t. You can either lift it or you can’t. There will be good form and bad form, but moving the weight through a limited range of motion sometimes makes training less complex and therefore less open to problems.

Is there an optimal exercise? Well years ago in the Health For Life manuals by Jerry Robinson he made serious pitch for the close grip pulldown done with a change in torso angle AS you did the exercise. You started bolt upright with the weight giving you a nice starting stretch. Then as you pull the weight to the lower sternum, you arch very hard and lean back slightly with NO use of momentum. He claimed that the "fan-like" shape of the lats needed this particular voodoo to emphasize all the fibers. You could also use a close grip chin with a "triangle" handle slung over the bar. In fact the Iron Guru Vince Gironda claimed that REAL chinning or pullups meant bringing the bar to your lower pectoral region. He said you could progress to pulling the bar to your waist like Mohammed Makkaway did when you were developed.
That would leave the rowing motion. You can do one arm, barbell, end of the bar, or even cable rowing. That was the old days. Now we have machines that take out the weak link, or low back. I consider this a VAST improvement over the old days. By rowing with a barbell, you were limited by both your low back and the strength of your arms. With a machine like the ones Hammer makes,.. There are two BIG advantages. First, your chest is braced, taking out any need for low back strain. The second bonus is that you can do lat shrugs or "Kelso’s" at the end of a set of rows. In other words, you can still contract the lats after the arms get tired. Kind of a two for one special.

The last thing to address is some sort of training template. I would start from hardest to easiest. Focus on measuring rest, good form, and proper volume vs intensity.

2. Rows on a Hammer Machine. Load up the machine to a decent weight and jack up the reps. Once again try five sets but do about eight to ten repetitions. At the end of a set, do the same amount of Lat Shrugs or "Kelso’s". This way you are exploiting that particular function of drawing back the shoulder girdle to a greater degree. Remember, as you row, keep the shoulders down, pull the shoulders back, and shorten the distance between the base of the neck and your tail bone. In other words, arch your back.

3. Pullovers. Few will have access to a Nautilus or other pullover machine. Even fewer will have proper instruction. That means you will have to do the old cross bench dumbell pullover. This is a common exercise that most trainees are familiar with. Back in the day, Arnold, Franco, Zane, and others ALL used it. You can add considerable benefit by stopping with the weight over your forehead instead of bringing it over the chest. This eliminates the restful range of motion where the muscles aren’t under tension. No rest for the weary. Without a machine for safety, stick with higher reps to limit the size of the dumbell. Higher reps means less total sets. Try 3 sets of 15 to 20 reps.