IPF, IPFW, or IPFILTER?

[Andy Firman]

The author of the FreeBSD handboodk prefers IPF (ipfilter) because 
its stateful rules are much less complicated....  
The author of "The Complete BSD" talks about IPFW (ipfirewall)
only.  People on this list talk of PF (packetfilter) quite a bit.

What is the most "commonly used" firewall for a web/email host 
server with a static IP address connected directly to the Internet?
(protecting itself)

What is the most "commonly used" firewall for a gateway/router/
network firewall server in front of several other boxes?
(protecting others and itself)

Thanks,
Andy