I just moderate all of them.

I like WP Spam Free, although I don't think it's the best. There are plenty of free options out there.

Minimum Comment Length is a good one.

Antispam extra also looks quite good, but never used it. Any plugin which removes links from comments will do the job in place of it.

This seemed interesting : I am an akismet user, while looking for alternatives you might like, this came up:

WordPress › Cookies for Comments « WordPress Plugins

(copy/paste from their description, credit to the source linked above)

This plugin adds a stylesheet or image to your blog's html source code. When a browser loads that stylesheet or image a cookie is dropped. If that user then leaves a comment the cookie is checked. If it doesn't exist the comment is marked as spam. The plugin can also check how long it took a user to enter a comment. If it's too fast it's probably a spam bot. How fast can a legitimate user enter their name, email, web address and enter a well thought out comment?

:

I haven't used this plugin but actually seems pretty cool. BUT, if the user is blocking cookies in browser, or something happens with the session/etc, there could be problems with legitimate users posting.

BTW, Akismet is free for personal blogs; if you are relatively small in your own business, you might be able to fly by under the radar, so to speak. Paying for the service is worthwhile for business blogs and they do provide a good service, so I support them.

Growmap - its one of the best and if you look at some of the bigger blogs around its what they all use. I have it on all of my sites after growing tired of akismet

wordpress comment spam