MailChimp for newsletters and SendGrid for everything else. That's a winning combo.
From my understanding, and having used Mandrill for some time, it can be used for anything you want (that follows its double opt-in, no spam requirements).
"Use Mandrill to send automated one-to-one email like password resets and welcome messages, as well as marketing emails and customized newsletters."
Emphasis on the "as well as marketing emails and customized newsletters" section there.
The difference of Mandril is that is doesn't have all the fancy features of Mailchip that people "would expect" to create a newsletter etc so Mandril is aimed at developers/software etc. That does not mean you can not use it for same uses as Mailchimp though.
Huh?
Are you sure you have configured it correctly, including DKIM?
We're using SES a lot (both transactional and campaigns) and never had a problem with deliverability.
There are too many spammers using it.
That seems unlikely considering the default sending limit is a mere 10k mails/day (iirc) and I doubt Amazon lets you raise that when your complaint-inbox is overflowing...