In my view All in One Seo pack is the best seo tool, and on the 2nd number SEO by Yoast.
but mostly people like seo by Yoast plugin.
Best SEO tool is Ahrefs, its costly but you can buy it in cheap price through group buy sites.
Here is the list of best seo wordpress plugins
All in SEO Pack
Platinum SEO Pack
SEO Smart Links
and the best Backlink tool is Ahrefs and SEMrush for Keyword Research.