Spam comments are frustrating and preventing them can be hard to get right but an important part of having a successful site. Below are some recommendations for ways to prevent/combat spam comments. There are many great options not listed here, these are just soluitons we tend to use.
Kadence reCAPTCHA Plugin (Pro Membership)
As part of the Kadence membership, we offer a reCaptcha plugin that allows you to add Googles reCaptcha to comment forms. More than that though you can add to registration forms, login forms, WooCommerce checkout, and reviews.
Comments Blacklist Manager
Built into WordPress is a comments blacklist that allows you to add words/phrases that are found in a comment will automatically move that comment to the trash on your site. You can manually add things there but using the Comments Blacklist manager plugin you can pull in a custom list of common words/phrases used by spammers.
A great tool that gives you settings that can greatly reduce/prevent spam. It’s a more complete solution than comments blacklist but without using reCaptcha or running your data through a paid service like Akismet.