ChipMixer easily has the best and longest standing reputation among all bitcoin mixers.
A point to note though: Do
not find the link to use via a web search. The number of fake and malicious clones is staggering. Here are the only two real links (Tor preferred both for privacy and security):
https://chipmixer.com/http://chipmixorflykuxu56uxy7gf5o6ggig7xru7dnihc4fm4cxqsc63e6id.onion/You can verify these links are correct in their official thread mk4 linked to above.
CoinJoin service: Wasabi / Samourai / JoinMarket
Wasabi now spy on their users and censor transactions, so I would no longer recommend them.