This is pretty complicated question.
Generally all top rates SEO plugins for WordPress are very similar and doing exactly the same, so you can choose any of this:
1.All in One SEO Pack
3.Platinum SEO Pack
The above plugins will take care for the basics.
There are secondary recommended plugins for WordPress and those are:
1.Google XML Sitemaps
2.SEO Smart Links
3.WP Related Posts
Not really popular WordPress plugins for SEO that I would recommend are "WP Smush.it" this will take every unused information and reduce size of the images, which is very important for website speed.
Again as website speed is very important, "W3 Total Cache" can speed up website and cache static content.
SEO Pressor is paid plugin, but it also can do excellent work assisting with on-page optimization, but personally I think it is not necessary.
Let's not forget that SEO rely on 2 factors - onpage and offpage optimization. The above are only related to on-page factors, so link building is mandatory part of SEO and key to achieve higher SERP.