You should set a blog commenting policy early on so that you give your readers and commenters a clear statement of what you will and will not accept in comments.
WP-SpamFree has some advantages over Akismet in that it require a cookie to be set in order for a user to post a comment. This blocks comment bots.
DoFollow allows bloggers to reward their commenters by providing them with a backlink that is recognized by search engines to their site.
KeywordLuv is among one of the most heavily abused features of Wordpress blogs by spammers or commenters who add little value and try to steal backlinks.
I will be installing the WP-SpamFree wordpress plugin to see if it helps reduce the number of spam comments in my pending bucket.