is this an appropriate question for site?
Not at all. There are several problems with this question:
It is the nature of such services that most people use them exactly once in their life. Therefore almost nobody can vote for more than one answer. Of course, some dedicated study could do this, but I doubt that something like this exists in this domain. Moreover the quality of such a service is very subjective.
Self-advertisement answers will be very difficult to distinguish from honest answers.
It’s a shopping question. It would even would be a bad question for this site if you specified a subjective criterion (not that I have one to suggest).
The number of possible answers is very large.
I don’t know about this special kind of service, but I would not be surprised if most of them are not actually about advising you but doing the entire job for you – which would be unethical.
The Quora question you linked pretty much proves my points: There are a lot of answers and most of them are blatant advertisements, including some that overtly advertise unethical services. The question has essentially degraded to post your advertisement here.
What you can ask about here, is how you best choose such a service (without naming any particular one). Then all of the above problems would vanish.