I have tried a lot of dating sites over the last 5 years. I am an old guy (50s) so this may not apply to the younger generation who use cell phones and the dating apps which I personally find to hard to read since they are small screens.
I always keep going back to Plenty of Fish. I use it for a while, get pissed off at the low response rate and go out and try other sites. In the end I always come back because while it has its problems (and there are many) it is still the one that I get the most responses from. The only other one I would recommend is Match.com but it does get expensive if you are using it for 6 months or more.
Food for thought