Most "best UX agency" lists are built to rank, not to help you choose. Some are paid placements. Others are written by agencies to appear in exactly this search. Either way, they can't know your problem.
Here's a better test. It takes one meeting.
A ranking works when there's one clear measure, like a race time. Choosing an agency has no single measure. The right partner for a new app is the wrong one for a government service. The team that wins design awards may never have fixed a product that customers are already leaving.
Lists also reward what's easy to see: visual polish, famous logos, award badges. What matters most is harder to see: whether the agency changes the decision, not just the design.
Most briefs fall into one of three types. Each needs a different kind of partner.
An agency that's excellent at one of these may be average at the others. Ask which one they're best at. A good agency will tell you.
Ask these five questions. The answers tell you more than any list.
1. "What would you do if your research said our brief was wrong?" A strong answer names a time it happened. Heidelberg Materials brought us a communications brief. The research showed the real problem was in operations: cancellations, scheduling and delivery delays. Staying inside the brief would have meant polishing messages about a problem messaging couldn't fix.
2. "Who will do the work?" Meet them. The people in the pitch should be the people in the research sessions.
3. "Show me a decision your work changed." Not a nice design. A decision, and what happened after it.
4. "What wouldn't you do for us?" Good partners know their limits. An agency that says yes to everything is guessing about half of it.
5. "How will we both know it worked?" Listen for a measure agreed at the start, not a report at the end.
Use lists to build a shortlist, never to make the decision. Then run the one-meeting test with three agencies. You'll know within an hour which one understands your problem.
For a shorter version, read how to choose the best UX agency for your needs.
Related: Our services and How we work.