Nothing lights a fire like being told a specific competitor is beating you for a keyword you care about. That's the whole angle.
Building the data
Use Similarweb and Store Leads to find a prospect's top organic keywords and who ranks above them, then enrich with the branded terms and SEO phrases their product should own.
The angle
"[Competitor] ranks above you when people search '[keyword]', and they're winning that traffic on ads too." It's concrete, it's competitive, and it hands you a reason to talk that isn't generic.
For a marketing-agency client, naming the exact competitor and keyword, and how to beat them without waiting on SEO, was the difference between a skimmed email and a booked call.