What do you think will be the best and why?
The best will come from programmable privacy. Look at some projects that are being developed: Blacknet, Aleo, DarkFi.
Zcash uses zk-SNARKs, which are very good, but they need a trusted setup, which is risky.
Modern zk-SNARKs, like their Halo2, don't rely on the trusted setup.
Programmable privacy would work if the masses cared that much, but you can show them the most amazing stuff and if it involved 5 min extra of work.. you already lost lol. Until the need arises, privacy just aint that popular. Everyone looking for the 1 button solution to their privacy issues and then they get taken and eating up and they boil like the frogs in a pot on the stove... thinkin they livin a great life as they slowly boil.
I liked aleo when it was zexy... their a bit too corporate for a pirate like me, but the library they building for zkp arrr incredible.
Forunately I trust only myself, so seeing how they receive funds is a big trust issue for me, not to mention drkfee choosing PoW... my faith in grassroots is dwindling...
Also research
https://zeroknowledge.fm/the-power-of-tau-or-how-i-learned-to-stop-worrying-and-love-the-setup/...that also a great site to learn more about ZKP tech