Lot's of people don't rate boxing yet it's one of the core things I teach my little workout group first. Basically you need to be able to hit without being hit and boxing offers a lot of solutions and best of all anybody can do it.
There really is no excuse not to train it, boxing is cheap to learn and train. Equipment is a pair of decent boxing gloves, groin guard, mouth guard and possibly head guard. Boxing is a dangerous sport, in my family by tradition we don't box hard after the age of forty, as repeated head trauma will cause issues later in life. However being forty three I still light spar.
One of the best things boxing gives you is the ability to deal with real time pressure of someone trying to hit you. Most people who will try to hit you in the street situation will fire something that resembles basic boxing and sparring will teach you to deal with attacks and land your own. It's rather funny but the people who most berate boxing for not being real world, are the people who seem to get knocked out quickest. Being able to relax whilst under pressure is a key skill for self protection.
Boxing hands blend nicely with other martial arts such as silat, judo etc. The style of boxing I was taught is a blend of old style English boxing and later I went on to mix it with some Filipino boxing. I have been going to martial arts workshops since the early Eighties and there is a certain sense of satisfaction and well being that you get from knowing how to box. To be honest as a thirteen year old, I did not pay to much attention to some of the old style boxing I was being taught, however since my research into systems like Silat and Kali, I can see a lot of interesting shapes that I also seeing in our family style.
In the older style I studied, I was also taught basic clinch and throws and because it was based on bare knuckle fighting, we were taught to throw punches from a different stance and also to cover differently. We were also allowed to grab and hit. Once you get that relaxed skill, you can start to blend it with your other arts.
One of my silat teachers used to say silat is boxing when all the fighters have one or two knifes.