I have used a few senior dating sites, but I can't really speak for which ones are the best, or which are worth your money. That's up to every individual person and how much they like the profiles they find.
But here are a few I have tried before.
1. Silver Singles - Pretty good site, a bit simple and old fashioned, almost no free preview, but good selection of smart, educated over 55 adults.
2. FriendFinder - Friendfinder (also called Adult Friend Finder) has a lot of over 50 profiles. Granted this is more of a swingers dating site, because of a more liberal sensibility. But still worth searching.
3. Our Time - Very similar to Silver Singles, maybe a little bit more modern. Not much of a free preview in my opinion.
4. eHarmony - Really smart site, though it's not relegated to just over 50. It's a site that matches people according to personality, values, morals, and beliefs. Probably the most serious matchmaking sites.
5. Zoosk - Zoosk has significant numbers of over-45 members. What people like about it is the video friendly streaming abilities. Just meet people face to face instantly like speed dating.
6. Match - Older demographics here, lots of filters which is good, good number of members, not the most exciting site in the world, but pushes meeting in person.
7. Christian Mingle - Has plenty of Christian over 50 singles.
8. Elite Singles - Lots of over 50 members but they tend to be college educated, successful in business, sometimes CEOs or workaholic entrepreneurs. Kind of a crapshoot here.
9. Senior Match - Longstanding senior site with almost 2 million people and very good customer service.
10. Date My Age - Doesn't strike me as a senior dating site, but does have accommodations for many people over 50.
11. Senior People Meet - This one seems different and actually talks about having someone meet with you and discuss your wants, needs and dealbreakers. This is a matchmaking company not just dating app.
12. Talkify - Same deal as Senior People Meet, but the Rolls Royce version, with custom made dates and constant coaching from a relationship specialist.
There probably are more, but these were the ones I've either tried or looked into.