It depends on whether you need to maintain access to the address.
Temporary addresses are probably more anonymous. But are treated with very significant suspicion as a result. Which often means anything you try to do will just get blocked.
If you need to maintain access to the account I’d probably go with Tuta or Proton leaning more toward Tuta which doesn’t support recovery contact details.
Do bear in mind that both of them will enforce all legal orders and that there are very much limits to how much privacy and anonymity you can actually get when using email.
Email is also very commonly abused for things like spam and these companies have to take such abuses seriously or risk getting the entire company blocked by other email providers.