which content filter is best?

I'm not entirely sure where to put this message, like in what newsgroup,
so because firewall appliances and some routers usually come with a
content filter provided by one of these 3 companies, I'm interested to
know which one you all prefer or which one you think is better.

I'm interested in what your opinions are for Websense, Cerberian/now
blue coat and then N2H2. My reason for these 3 is that I belive they are
the most widely used, and surfcontrol. I am getting this week on
Thursday a Sonicwall TZ150 and have the option of Websense, Cerberian or
N2H2 for the content filtering.

I've had experience with Cerberian over the last year, but none with
N2H2 and Websense. I currently have a Belkin 802.11g wireless that uses
Cerberian and I've found it blocks more pages better then using
Cyberpatrol software which uses surfcontrol for the web filtering.

I'm just wondering what people think of N2H2, Websense and Cerberian.
One thing I'm wanting to know is that I've read at www.sonicguard.com
that there's newsgroup blocking for the sonicwall devices like if you
enter in sex as a keyword then many alt.sex groups would be blocked from
nntp. However I'm not sure if that's true in the current sonicwall
devices and stuff.

I'm interested if anyone has any experience with N2H2 and Websense to
see how good the filtering is and if they can block nntp newsgroups by
keywords or something.