Before you answer, please know that I read A LOT of posts on here about this topic... However... I have been using Yoast for over a year.. My page rank is at 1/10. Not great.
I use a Firefox toolbar that tells me what the PageRank is for a site.
I did a Google search for Best SEO plugin and came across SEOPressor. I know it is NOT free, BUT when I tested the SEOPressor website with the page rank, it is at 6/10. That is REALLY good and it's very hard for a page to rank so high.
I know everyone likes Yoast and Ultimate, but it just seems like the SEOProsser having that type of Page Rank is doing something right.