Former Mr. Texas give his answer as to what is better!
The only real benefit of lifting heavy is it makes you stronger. Lifting heavy activates more fast twitch muscle fibers giving you more explosive strength which is great for power lifting and Olympic lifting. I recommend lifters train in both the lower and higher rep ranges to active fast and slow twitch fibers. The low rep range will help build strength while the higher reps will help with hypertrophy ( building the muscle).
*There is a bazillion videos and articles with PHDs arguing on what type of lifting is better. The general answer is different strokes for different folks.