All seem to be bad or evil and stupid. Not tried Afternic, maybe it is good (don't think so, buyers are GD agents).
Epik was acceptable/good until yesterday. And now they are hiding buyer's info for GDPR reasons, what a nonsense. Sellers need to be protected, not buyers. And buyers give their info knowingly. They don't have to give their info. GDPR is for domain owners, not domain buyers.