As mentioned earlier, every case is different, and the success rate varies from person to person.
However, like in the case of eHarmony, you know that only the ones seeking a serious relationship would be willing to put money into a dating site.
Therefore, most people on such paid websites and apps are on the same page as you. That is, of course, if you are looking for something long-term.
On the other hand, if you simply want to hook up and have one-night stands, the usual set of popular apps should work just fine.