With past experience with both, and a few cutting cycles, I'd say diet: 70%, cardio 30% importance in getting ripped. Calorie defecit is key. I did a low-carbish calorie defecit and went from 12% to 8% in 8 weeks - every week was 0.5% very steady (use good calipers, which aren't accurate in an absolute sense, but work great for week to week measurements)
However, I always prefer adding primo or var (no real preference) to keep muscle during this time. Hardly any muscle gets added during this phase, but at least what's there doesn't waste away.