Most mixers introduce points of centralization, which allow a party to steal your coins or allow them to break privacy.
JoinMarket is a good solution that works on Bitcoin today.
Monero is a good altcoin which will automatically mix your coins using crypto. I believe it is more powerful than JM but requires using an altcoin.
Zcash offers unmatched anonymity powered by fancy new crypto (less tested, less certainty on the security, but much more powerful). Still under development, but I'm guessing will be more ready in August.
JoinMarket is a good solution that works on Bitcoin today.
Monero is a good altcoin which will automatically mix your coins using crypto. I believe it is more powerful than JM but requires using an altcoin.
Zcash offers unmatched anonymity powered by fancy new crypto (less tested, less certainty on the security, but much more powerful). Still under development, but I'm guessing will be more ready in August.