If you had asked me this question several months ago, my answer would have been, hands down, Rank Math.
Rank Math packs a lot of features in such a small package.
It's also very easy to use.
But the recent chances to Rank Math, where they basically put in all sorts of keyword and content enhancement features, have really turned me off to them.
It's as if they've bloated what had otherwise been a smooth, slick, and easy-to-use plugin into just basically giant advertising for their premium product.
I'm seriously considering basing all my new blog projects in the near future on the free version of the Yoast SEO plugin.