Safari: Adblock, Hush (will stop the day any FOSS browser becomes closer to it in speed and resource usage; I doubt it as Safari literally comes baked with OS)
Firefox: uBlockOrigin, AdBlocker for YouTube, Adguard, Disconnect, DDG Privacy Essentials, Sponsor Block for YouTube, Unhook (Firefox is used very little, just because compared to Safari it is still sluggish on Mac)
On iPhone: tried NextDNS (and few more things) but result was such a mess that I stopped.