Depends on your needs

SimpleLogin is an email alias, so it is hiding your real email from others but also directly tied to it. SimpleLogin says they don't access any info, but we can't verify that. Best to assume and keep in mind they know which aliases belong to your email if you aren't self-hosting. I think it is still useful for everyday stuff.
simplelogin.io/faq
simplelogin.io/privacy

Burner emails on the other hand aren't tied to your email. If you want no connection to your email, burner emails like the ones above are the way to go. Downside is they're usually only temporary.

Also, check out Addy, a competitor to SimpleLogin. You can pay with Bitcoin or even Monero if inclined. They answers a lot of questions here:
addy.io/faq
addy.io/privacy