If the number of businesses you have is relatively low (<1000), you need to understand them well first. Which are your top performers, which are weak. Cluster them by net revenue generated in A (top 15%), B (next 35%) an C (rest). Then you need to understand how you attracted A and B customers and focus your marketing / sales activities on those channels.
Churn / Retention of customers is important for you as well. Are you loosing more customers than you attract? Why do you lose them? How can you make them stick?
I will be publishing a cohort analysis template soon, which should be helpful for you.
Regarding your question: You should be looking into net revenue generated if the commission per business varies. Change orders / customer to customer lifetime in months/years. Change basket size commission, to understand which channel attracts more valuable customers. I assume conversion rate does not matter for you at all. Assuming you are <100 new sign ups / month.
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