I've tried three sites mainly:
Match: For me, the most productive in terms of dates and conversations, however the profile photo album usability has been poor for years - for some weird reason, you can only use certain photos from your profile as you main photo. If you upload a lovely new photo, you won't necessarily be able to use it as the main photo without deleting another one. It's very bizarre and inconsistent. I've had many rows with them about it. Infuriating and basic to resolve, but still it's poor. Actually, the whole website has had little upgrade in terms of the basic profiling/matching, but some new things have come along, such as live chat rooms with themes.
I've also had many rows with them over their promotion of the paid membership stating that you get 'unlimited messaging'... my argument being that it is actually VERY limited, given that a user can only reply to you if they ALSO have a paid membership. What's the point in messaging someone if they can't reply? I might as well message a brick wall, or bribe another user to reply by covering their membership too. That is very limiting for a dating site.. hardly going to lead to a date is it?! So I've always bought the additional add-on to ensure anyone can reply.
They often do deals and it's worth waiting for those (or complaining, like I did, and getting a deal offered to you by way of apology).
POF: Recently, you can only send one message per day with a free account. Before this, it was worth using because it was entirely free, but I only ever really had a couple of meaningful exchanges, and unfortunately the only promising one was during the pandemic, which wasn't sustained long enough to make it real. I always got the impression there were lot more people on there looking for casual hookups, and also a lot more fake/spam profiles.
Asexual Cupid: I'm on the Ace spectrum and this website is becoming quite significant. I'm paid up, it's reasonable and I've had more contact/dates from this than any other. Obviously it's limiting in terms of numbers registered and finding someone within proximity, but it's certainly gathering pace, and also useful for making friends who share the Ace thing. Weirdly, locations are abbreviated into three letters.. so DOR could mean Dorchester or Dorking or Dortmund..
Pacattack touches upon a key point - there's no point continually seeking refuge online/behind a screen - get out there socialising! It's scarier.. and often later in life it will mean taking up a new hobby or trying somewhere/something outside of your comfort zone. I have plenty of hobbies, but none of them are yielding results.. so now I'm considering taking this advice myself and trying a gym class or new hobby.
Wishing you the best of luck!
TTG