What are the email services for (nodemailer, sendgrid, mandrill, etc...) nodejs/express application and which one's do you prefer and why?

As the question states I am in a bit of a predicament with what email service to go with. This is the first time I have really developed in nodejs with express and want to do a couple things with emails:

1. I would like to be able to send an email when a user signs up that verifies his/her email and won't let that user sign in until such this is completed.
2. I would like to be able to send email notifications to users, who lets say comment on another users post for example.
3. Be able to send all users in a certain group (i.e. roles of admins) an email.

These are just some of the things that I am wanting to do and I am wanting to know your opinions on which service would be best suited for these kind of actions. And if you like one email service over the other please specify why.

Thank you in advanced.

via Taylor Austin