More people, or less exposure
Almost every reason for leaving Sniffies is one of those two. Grindr solves the first: same idea, far bigger pool, and proper blocking and reporting. Pure solves the second: anonymous, temporary, and the highest safety score on this page.
If you want a conversation, change the format
No map-based app is going to give you slow conversation, because that is not what it is for. Feeld and HER both have profiles worth reading and crowds that expect a chat first, which is a different experience rather than a better version of the same one.
What you give up
Cost, mostly. Sniffies asks for nothing and works in a browser. Everything here has a paid tier and wants an app on your phone, which matters if discretion is part of why you were using a website in the first place.