Postfix is #9 in Top 10 Email Servers
Postfix attempts to be fast, easy to administer, and secure mail server. The outside has a definite Sendmail-ish flavor, but the inside is completely different.
Positions in ratings
#9 in Top 10 Email Servers
Alternatives
The best alternatives to Postfix are: iRedMail, Microsoft Exchange
See also:
Top 10 Email Servers
Top 10 Email Servers