I have tried somewhere around a dozen spam blockers that don't require me to manually cull through a few hundred pieces of spam and rescue the false positives. Finally. This Wordpress plugin delivered: Antispam for all fields.
I still get emails with my potentially spam comments but only a few because it allows me to zap the mess out of them so they'll never show their spammy faces again. It's also quite easy to approve a false positive if someone does get caught. Instead of 50+ spam comments a day, I'm getting less than a dozen emails. Lovely.