Ask HN: Best provider for sending transactional emails?

I am building a web app that will send SEO reports via email and I am on the lookout for a decent provider to deliver emails.

I understand that Amazon SES is the cheapest when it comes to sending emails. I am not sure how good their email deliverability is.

Other options are Postmark (somewhat pricey), Mailgun and Sendgrid. I would like to know which email providers are preferred by the HN community.