Great question.

I’m both – you can’t ignore the evidence that’s been before our eyes for years. All rep ranges (until we get to endurance training) build muscle, but pumping builds more than powerlifting.

My preference is progressive overload across a range of reps to create a physique as strong as it looks, plus there’s a denser look to someone whose lifted heavy weight compared to his equally sized counterpart. This may not be a muscle fibre thing as much as certain muscle groups (e.g. traps) being more developed.