I'm not talking just pull-ups as if they're the Zeus of Pulling Mount Olympus, it goes beyond that. It's pulling from an overall perspective that is the key thing here. It's not merely a method of training to help with muscle imbalances, it's more on the likes of building grip strength, working with various objects and having the strength to help yourself up or others. Machines, Deadlifts, Pull-ups, Chin-Ups all work to a degree within each other. No one move is superior to the other and no one movement is going to solve all your needs in that area.
When you learn to get better at pulling, you're getting strength that is essential in ways you may not even realize. From my own experiences, I may not be the best at pull-ups but I've done a lot of pulling in my time, more than I lead on. It truly started when I was laid up after my accident and being in a hospital bed was very discouraging. If you've had major injuries or have/are wheelchair bound, you have an idea of what I mean. It wasn't easy for people to lift me in order for me to do what I needed to do so I made it a priority to use what strength I had in my upper body to get myself around which turned to more pulling and dipping. In the hospital, they have those hangers where you pull yourself up to get into a wheelchair or to pull yourself up in order to sit up. I did a lot of those and when I had to get into a car without using my legs, I had to pull and grip on the Car Handle basically with one arm in order to get myself in. One time, I had to get in the passenger seat this way and I said to myself out loud "Come on motherfucker" in order to muster the strength to get in.
Pulling isn't as big of a priority as pushing is but it is important to understand that Pushing and Pulling is the Yin and Yang to the Upper body and be able to work with both in a synergetic fashion. I like to do Pull-downs, Rows, Pull-ups & Chin-Ups when I train especially when I use my Fat Gripz to really utilize the muscle groups as best as possible to their maximum potential. I love to use the WorldFit Iso Trainer and make it work as a Suspension Trainer, you can do so much with it, the list is only limited to your imagination. From Isometrics to Partials to Full Range as good as can be, this thing can do wonders for your pulling strength. One of the best authors on Suspension Training is Matt Schifferle with his Grind Style Calisthenics Training System. It teaches the true fundamentals of Pulling along with the other chain of muscles so you can build muscle and strength.
An idea of doing various pulls is a video demo I did where there are exercises such as the Hybrid Iso Pull-Up by strapping a loop on each side of a rack or in this case Monkey Bars and pull yourself up until the strap has you at a stopping point and hold it. This is essentially a 2 For 1 Exercise as pull with with as much strength from an Overcoming POV and you're fighting against Gravity at the same time. Another exercise is a beginner's version of Pull-Up where you squat down and hold onto the handles and then pull yourself up using your legs as assistance but also do your best to focus and use tension on the muscles of the back, arms and core. This version is a great strength builder and puts on muscle in the upper back. The last one is the Hybrid Iso Row where you create a stopping point and then row until you hit that mark and hold it. Hell of a grip and core exercise.