Pyzor, Razor, and DCC?

[Matt Kehler]

Forgive my ignorance..I'm fairly new to this :)  Can someone explain (or is there a good FAQ) the pros/cons of using Razor vs Pyzor vs Dcc?  I've checked the websites for them all, and searched the MailScanner list archives....but they all look fairly similar in function, and I am assuming using more than one of them would be redudant. Does one of them work better with MailScanner/Spamassassin than the next?  Is it simply user preferance?  This would be in a system wide config; not personal use.

thx
Matt