For adult?
If you can get approved for Amason SES (I'm finding it hard these days but others have success), that combined with a $69 copy of
Sendy is pretty good.
Really depends on what kind of content you're sending, how many emails, how many users, what kind of features you want, etc etc.
I'm moving some stuff over to
Email Octopus but haven't used it enough to offer a full recommendation.