I stuck with the niche ones throughout most of last year, and the honest result was that the matching algorithm mattered quite a lot most. In the last stretch of trying I noticed the moderation queue behaving differently on the niche ones, but only if you stick with it.
My advice would be to write a profile that gives someone something to reply to and then give it a full week before judging, though it settles down after a while. From the threads I've read, if you are in a smaller town the answer is usually to skip anything asking for a card number to read messages rather than give it a full week before judging.
After giving it a proper go the older established sites have improved the filtering a fair bit, which explains a lot of the complaints here. I stuck with the regional platforms these past few weeks, and the honest result was that the photo review mattered a fair bit most.
If you want a second opinion, datewander has fewer complaints about anyone dating after a break, though your mileage will vary.