MeetMindful: Some of the smaller dating sites promise more thoughtful connection and match curation, which is what my clients who are ready to settle down desire. As I'll get into next, it's not exactly a numbers game.
Match and OkCupid both have a wide base of users, which means more access, but it's a toss-up if you'll find people actively using the app who are your type on any given day.
Hinge, OkCupid, or Match: Consider if you want to go a little deeper than swiping, Hinge allows for more engagement with a profile, the user experience is pretty seamless, and many of my clients find success there. Bumble: Try if unsolicited messages make you nervous and you want more control over the messaging process (since women make the first move). 
If you're looking here, just know that because it's the platform with the most users ( 8.5 million to be exact), you might have to weed through even more options before landing a connection.