When I was single, I had the most luck on OKCupid. It had the nicest people, and their site's questions and profile structure encouraged good profiles so you could really get a feel for someone. I met some really good people through OKC.
I also used PoF, but as I've often said on here before, PoF is like Walmart. You have to search through a lot of freaks to find the other normal people.
Okcupid and Plenty of Fish😊 They are free and mostly caters to young people trying to get to know each other. I met my best friend on Okcupid and my boyfriend on pof. They are the only ones i've ever met online so i guess im lucky haha😋