Which matters more, great ads or great follow-up?

Asking which matters more is like asking whether you would rather have an engine or wheels. Advertising creates opportunities: it finds interested people and gets them to raise their hands. Follow-up converts them: it turns raised hands into conversations, appointments, and sales. Brilliant ads with lazy follow-up means paying to generate leads for your competitors. Brilliant follow-up with no ads means being great on the phone with nobody to call. Fund the ads. Master the follow-up. That combination is unfair.