What the engines tell you to look for#
Every one of the 12 answers named a measurement plan. Prefer Managed starts with one: a day-zero baseline on your tracked prompts, which its 90-day guarantee is measured against. Prefer asked ChatGPT, Claude, Gemini and Perplexity this question three times each on 13 September 2026 and counted the criteria they gave.
| What to look for | Answers |
|---|---|
| A measurement and reporting plan | 12 |
| Verifiable case studies | 11 |
| A pilot or short first contract | 9 |
| A method that differs from ordinary SEO | 9 |
| Technical SEO skill | 7 |
| Off-site work and digital PR | 7 |
| Entity and schema knowledge | 7 |
| Fit with your industry | 6 |
The engines agree on the top two and split below that. Gemini never mentioned a pilot. ChatGPT was the only engine that did not list a distinct method as a criterion, though all three of its answers told buyers to ask how the work differs from SEO. Claude answered all three times without citing a single web source.
The red flags they name#
| Red flag | Answers |
|---|---|
| Guaranteed placement in AI answers | 11 |
| Ordinary SEO renamed, with no new method | 8 |
| Mass AI-generated content | 5 |
| A long contract before any baseline | 5 |
| No explanation of the method | 5 |
Guaranteed placement is the red flag nearly every answer shares, because no agency controls what an AI engine says. A guarantee of measurable lift is a different thing: it names a metric, a time window and a remedy (what a real guarantee looks like). Only ChatGPT warned about agencies that claim a secret method or a special relationship with an AI company, and it did so in all three answers.
How to choose, in five steps#
- Shortlist three to five agencies. Perplexity’s answers suggested three to four or three to five, with no source. Before you call any of them, confirm a named owner and a real company, the first check in our agency rankings. Done when every name on the list passes.
- Ask each for its measurement plan in writing. It should name the engines, the prompts tracked and how often they report. ChatGPT suggested 25 to 100 customer prompts; our own guidance is to start with 10 to 50. Done when you can compare the plans side by side.
- Check two case studies. Ask for named clients and a before-and-after number, then ask for a reference call, as ChatGPT suggested: “Can you speak with a current or recent client?” Done when a client confirms the number on the call.
- Ask what they do that an SEO agency would not. Nine answers made this a criterion, and eight flagged renamed SEO as a red flag. The criteria point to the work: off-site authority and digital PR, entity and schema work, and technical SEO (7 answers each). One ChatGPT answer flagged any agency that “cannot distinguish GPTBot from OAI-SearchBot”. Done when they describe how they would do each for you.
- Start with a pilot. ChatGPT suggested a 90-day pilot “with defined deliverables, access to all data, and a cancellation clause”. Record your step 2 prompts, per engine, before work starts, and agree the pass mark in writing. Re-run the same prompts at the end. Done when the result meets the pass mark, or you use the cancellation clause.
Disclosure: we sell Prefer Managed, a done-for-you service, so we have a stake in how you choose. To bring your own baseline to the first call, run a free AI visibility audit.
Sources
- Across 12 answers to 'How do I choose an AEO agency?' from ChatGPT, Claude, Gemini and Perplexity (three runs each, 13 September 2026), the most-named criteria were a measurement and reporting plan (12 of 12), verifiable case studies (11), a pilot or short first contract (9), a method distinct from ordinary SEO (9), then technical SEO capability, off-site authority and digital PR, and entity and schema knowledge (7 each), and industry fit (6). (Prefer research note: AI SEO and GEO agencies (2026-09-16), dated research note)
- Prefer Managed, our done-for-you AI search service, costs $2,500 a month. Its guarantee: a measurable lift in AI-citation visibility on your tracked prompts against a day-zero baseline within 90 days, or Prefer works at no management fee until it is hit. We have a commercial stake in how you choose an agency. Prefer Managed (our product)
- The most-named red flags were guaranteed AI placement (11 of 12), an SEO rebrand with no new method (8), then mass AI-generated content, a long contract before any baseline, and no methodology transparency (5 each). (Prefer research note: AI SEO and GEO agencies (2026-09-16), dated research note)
- The engines split below the top criteria: Gemini recommended a pilot in none of its three answers, and ChatGPT was the only engine that did not make a distinct method a selection criterion, though all three of its answers included an interview question on how the agency's work differs from SEO. Only ChatGPT (all three answers) warned about agencies claiming a secret method or a special relationship with an AI provider. (Prefer research note: AI SEO and GEO agencies (2026-09-16, addendum 2026-09-18), dated research note)
- Claude cited no web sources in any of its three answers. ChatGPT cited 3 to 4 per answer, Gemini 10 to 12, and Perplexity 20. (Prefer research note: AI SEO and GEO agencies (2026-09-16, addendum 2026-09-18), dated research note)
- Specific figures in the answers, none attributed to a source: Perplexity suggested shortlisting three to four (one answer) or three to five (another) agencies; ChatGPT suggested a baseline of 25 to 50 or 25 to 100 customer prompts, two or three named case studies, a reference call with a current or recent client, a 60 to 90 day pilot or '4 to 8 week diagnostic or pilot', and a 90-day pilot 'with defined deliverables, access to all data, and a cancellation clause'. One ChatGPT answer flagged an agency that 'cannot distinguish GPTBot from OAI-SearchBot' as a red flag. (Prefer research note: AI SEO and GEO agencies (2026-09-16, addendum 2026-09-18), dated research note)
- Two of Gemini's three answers also explained AEO as Authorized Economic Operator, a customs certification, alongside answer engine optimization. (Prefer research note: AI SEO and GEO agencies (2026-09-16, addendum 2026-09-18), dated research note)
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