To first answer the immediate question, it is neither, I will explain my thought later on. Lets first start off by explaining what the two different training programs are.
What is High Intensity Training?
High intensity training is the name applied to different approaches to working out. Some people do high intensity training by going to complete failure by using a variety of different methods. Such as negative reps, forced reps, and partial reps, these extra movements help the muscle go to complete failure both positively, statically and negatively. However the more famous version of high intensity training is the one which was made famous by Mike Mentzer and Dorian Yates, it involved going to complete failure by using the methods above. However they would do two warm up sets and then hit the last set hard going to complete failure. This low volume approach would make them grow because right after a hard 45 minute session in the gym they would go home rest and eat. With each gym session they would grow stronger and there muscles would grow, overall they would not plateau because they would keep progressing by increasing their rep range or the weight.
What is Volume Training?
Most people know what volume training is because they either did it in the past or are currently doing it. However to the people that don’t know volume training, it is hitting the muscle from a large variety of angles and exercises. A person doing volume training would do pyramid scheme sets building up to their heaviest weight then dropping down to what they started with. Overall a large number of sets and reps would be done.
Which is better?
Neither because it depends on you the bodybuilder. Just because your friend grows like a weed using the high intensity method doesn’t mean you will to. Maybe volume training works for you or something in between. Overall we are all different, you have to find what works for you, only you know your body. So go find something that works for you!