Short answer — several specialist agencies consistently appear as leaders for law‑firm SEO in U.S. searches and industry rankings. Below are firms that show up repeatedly across Clutch, industry roundups and expert lists (with one-line notes and sources):

1. Rankings.io — well‑known specialist for personal‑injury and other law firms; high Clutch ratings and many verified legal case studies. (Clutch.co)

2. First Page Sage — boutique SEO/marketing agency that publishes an annual “top law‑firm SEO” roundup and ranks highly for law‑firm work. (firstpagesage.com)

3. Hennessey Digital — data‑driven legal marketing firm often cited for national personal‑injury and mass‑tort campaigns. (firstpagesage.com)

4. 9Sail — specialist legal/regulated‑industry SEO with strong local and enterprise experience for firms. (firstpagesage.com)

5. LawRank — long‑standing legal SEO specialist focused on organic rankings and conversion for law firms. (LinkedIn.com)

6. Consultwebs — established legal marketing/SEO firm used by mid‑size and local law firms. (loopexdigital.com)

7. iLawyerMarketing — niche local‑SEO and content-focused provider for family law and small firms. (firstpagesage.com)

8. Postali (and similar data‑driven boutiques) — named in recent “best of” lists as a data‑first agency serving law firms. (firstpagesage.com)

Notes and context

• “Best”/“leader” depends on your needs: practice area (PI, criminal, family, corporate), geography (local vs. national), budget, and whether you need content, local/GBP optimization, technical SEO, or large‑scale link/PR work. The lists above are compiled from industry directories (Clutch) and recent expert roundups (First Page Sage, Loopex/others). (Clutch.co)
• Rankings and vendor fit change frequently; if you want, I can: (a) pick the top 3 best matches for your firm’s practice area and budget, or (b) produce a short RFP template you can use to evaluate any of these agencies. (I can look up up‑to‑date client reviews or pricing for any of them.) (Clutch.co)

If you’d like, tell me the practice area, city/region, and approximate monthly budget and I’ll shortlist the 2–3 firms that are the best fit and pull current reviews/pricing.