There's FEELD, which seems to be really geared toward the GenZ / Millennial cohort, and is a lot more of a mixed bag than the other two (I like to call it 'Feels' haha). You'll find people and couples of every persuasion across the sexuality and gender spectrum there. And it's pretty wide open in terms of what the app is geared for in terms of who is looking for who.
There is also Sniffies, which is a web app (you have to go to the site, because it's too racey to be in the app stores). It's like a way raunchier Grindr. Differences are, there are a lot more anonymous encounters requests, full xxx nudity is allowed in the profile pics, and you can browse on a map instead of a grid. There are a lot more DL guys on there than the others, but everyone seems DTF (a lot more pump and dump offers there). While you might see people you recognize from Grindr and Scruff, it doesnt seem like as much of a neighbourhood scenester showcase as the other two.