Ideally a combination of both. Hypertrophy is stimulated via different pathways, i.e. heavy training and lighter training both create a different kind of stimulus that both lead to hypertrophy. So neither should be neglected. It's also vital for continual results in the long term to factor in progressive overload, and heavy weights on compound lifts lend themselves to that; conversely, some isolation movements exhibit very high levels of muscle activation (exercises like the leg extension are shown to elicit the most quadriceps activation in EMG studies, for example) which is great for hypertrophy, yet aren't suited to heavy loading or progressive overload, so are typically done with lighter weights and higher reps. Hence, do both.