I hesitated for a long time before booking my audit, because I didn't know which audit company to choose!

Here is a full list of all the companies allowed to do the Qualiopi audit https://travail-emploi.gouv.fr/formation-professionnelle/acteurs-cadre-et-qualite-de-la-formation-professionnelle/liste-organismes-certificateurs.

It's very difficult to choose on price, as the cost is more or less the same for all the companies. The only difference might be the frais de déplacement if you are having an audit in person (make sure you ask about this.)

Someone I know told me she chose the Afnor, because they are well-recognised as an auditing company. Another friend has an auditor who was more used to doing ISO certifications, and she told me her audit was horrible. 

In the end, I went on the recommendation of a friend who has a very small organisme de formation and worked with an auditing company who specialises in this. The company is called BCI (Bureau de Certification International France) and I was very happy to work with them. Feel free to email Djaffar Amar d.amir@bcifrance.fr and tell him that I sent you. He's the person that arranges the audits. 

I was able to speak to my auditor on the phone before the audit, which was really helpful.