Any editor you're considering hiring should offer to return a free line edit on a thousand-word-or-so sample, so I'll assume that that's what you're waiting on now. As with anything, you should send a sample to several editors before you decide on one, even if the first one seems great.
If you feel confident enough to look at all the returned samples and decide which are the best, go for it; but the problem, which is inherent and unavoidable, is that you're essentially paying someone to tell you what you don't know. In other words, if you could confirm which edits are the best, you would be able to edit it yourself and wouldn't need an editor, right?
So you pay an editor for their experience/authority, which, again, is problematic, since, as others in this thread have pointed out, a) experience doesn't equal expertise, b) fiction is so subjective that it's hard to say which edits are "best" anyway, and c) these editors are, ultimately, trying to sell you something.
Where does this leave you? Pretty far up the river, frankly. But there is a sliver of hope: If you accept that fiction is ultimately written for people to enjoy, then you can look at your story after the edits, and if it is now more enjoyable to read, then there's at least one fixed criteria, which is better than none.
Keep reading, keep writing, keep making mistakes, and keep learning from those mistakes.
Cheers!