This is the question I get asked most by small business owners, and the honest answer is: it depends on your timeline, not which channel is "better."
Choose paid ads first if...
You need leads or sales in the next 30 days, you're testing a new offer and want fast signal on what messaging works, or you have seasonal spikes you need to capture right now.
Choose SEO first if...
You're building for the next 2-3 years and beyond, your competitors are winning organic search and you're invisible, or your customer acquisition cost through ads is already uncomfortably high.
The honest middle ground
Most small businesses do best running a modest paid budget for immediate pipeline while SEO compounds in the background. Paid ads fund the runway; SEO reduces your long-term dependence on that runway.
If you're not sure where you stand, the fastest way to find out is to look at your current cost per acquisition across channels — that number usually makes the decision for you.