There is no single "best" SEO tool for WordPress, as the best tool for your specific needs will depend on your unique situation and goals. However, some of the most popular SEO tools for WordPress include Yoast SEO, All in One SEO Pack, and RankMath.
Each of these tools has its own strengths and weaknesses, so you'll need to test them out to see which one works best for you. Generally speaking, Yoast SEO is considered one of the most powerful SEO plugins available, while RankMath is a relatively new plugin that has been gaining a lot of buzz lately.