Best training method for gaining mass

On this forum I’ve been reading alot of posts where people are saying they get the best gains in size by doing powerlifting which I understand to be in the rep ranges 1-4.
On the other hand people say reps in the range 8-12 give best mass gains? who is right

neither, your training should be periodized so that you include times of higher rep hypertrophy training, and lower rep strength training.

Neither is right.

Both are right. Everything works for a while. The best training programs incorporate changes, typically every 3-6 weeks depending on speed of adaptations.

Instead of looking for the ONE program that will produce the best gains, strive to design a series of programs that will continue to produce the best gains. Once progress diminishes, move along to a new system.

Try them all.