My advice is to judge by quality and connection.
Begin by choosing three editors who appeal to you.
And by appeal I mean how they present and promote themselves and what level of testimonials they have.
And most importantly: make sure they offer a free appraisal along with some free sample edits.
Contact them, send the info they require to create said appraisal and free editorial sample.
A worthy editor will connect with story, voice, style, genre perceptions and conventions and supply sample edits (hopefully the full first chapter) that will bring improvements to your work and blow your socks into space at the same time.
You will know.
You will feel the connection.