SimpleLogin has fancier addresses, plus you can send from these

I’ve used 33mail.com for several years. Works perfectly.

SimpleLogin is cheaper and has a better interface IMO, though both are very good.

Note that with AnonAddy if you don’t have a proper DMARC setup you will not be able to send emails from your aliases, while SimpleLogin allows it.

I use SimpleLogin because the developer gifted me with a lifetime premium account because I helped him telling him he should drop proprietary dependencies and stuff that would help the service be more good for privacy users. but the GUI is prettier still

Both have a good privacy policy.

AnonAddy has set all the security features. Furthermore, their server mail server also utilises Opportunistic DANE TLS, STARTTLS, PFS, DNSSEC, MTA-STS, TLS-RPT, DMARC, SPF and DKIM.

You can check these information here

SimpleLogin lacks modern ipv6, a proper implementation of HTTPS, (doesn’t mean it uses http) content security policy and referer policy existence.

You can check these information here

I’d would use anonaddy.