How each one actually works
Grindr shows a grid of nearby profiles ordered by distance, in an app you install. Sniffies shows a live map in your browser, with activity plotted around you. Grindr is better at who is nearby in general, Sniffies is better at who is around right now.
Coverage decides it more than features
Outside larger cities Sniffies can look quiet while Grindr still has people. In busy cities the map is genuinely useful and often faster. Spend a week on both before forming an opinion, because local density beats every other consideration here.
Privacy is the real trade
Sniffies needs nothing installed, which matters on a shared or work phone. Grindr keeps more of its privacy controls behind a subscription. Both expose approximate location, so consider turning precise distance off wherever the app allows it.
What you get for paying
Grindr's tiers stack a lot of small conveniences: more profiles, better filters, fewer ads, incognito at the top. Sniffies Plus is one decision rather than three. Neither subscription changes who is nearby, which is the thing most people actually want fixed.
Safety
Both are explicit spaces with the usual risks. Verify with a video or voice call, tell someone where you are going, meet publicly first when you can, and treat pressure to skip those steps as the answer. Neither platform screens users.