I've tried a few WordPress SEO plugins over the years, from All In One SEO Pack to Robots Meta and then to SEO Ultimate; but that was before Joost de Valk (a.k.a. Yoast) released WordPress SEO by Yoast which is now my SEO plugin of choice for WordPress. If you want the definitive answer at who is the best SEO guy for WordPress, just do a Google search for WordPress SEO and see who ranks in position #1. That's one reason why I'm switching from to Yoast's plugin, and it has some other great features too like an awesome search results preview that helps you to optimise not just your search ranking, but also click-through rates.
Switching SEO plugins is no mean feat since you've probably already got meta descriptions and other information that you don't want to lose. There are also a few other tricks to migrating, so here's a step-by-step guide:
Installation and SEO Data Migration
Firstly, install and activate WordPress SEO by Joast.
While WordPress SEO by Joast can import data directly from several other SEO plugins, it can't handle SEO Ultimate directly. But never fear, because SEO Data Transporter can do the job, so install and activate it too.
Import the settings from SEO Ultimate using Tools → SEO Data Transport and selecting from: SEO Ultimate, to: WordPress SEO and Convert.
Disable SEO Ultimate and SEO Data Transporter plugins.
Configure WordPress SEO by Yoast
The WordPress SEO by Yoast settings appear in the main dashboard menu under SEO. I recommend you do the introduction tour to familiarise yourself with what the plugin has to offer.
If you've been using Yoast's RSS Footer plugin, go to SEO → Import and use Import from RSS Footer. Then disable the RSS Footer plugin as you won't need it any more. You could do the same for Robots Meta, but it's unlikely you'd be using that with SEO Ultimate.
Now go to SEO → Dashboard and set your main settings.
Select Disable date in snippet preview for posts, unless your posts are intentionally time-sensitive; generally you want to write evergreen content and you don't want Google's previews showing that your posts are “old” if they still contain great, relevant content.
Every now and then, some supposed SEO expert guy who claims to get paid thousands for his advice looks at my site for free and says “You don't have any keywords”, meaning that I don't have keyword meta tags. It won't help your search ranking since Google doesn't use keyword meta tags, but it will shut these guys up and possibly have them to keep looking for something that would improve your search ranking. Or maybe you want to just weed them out by leaving keyword meta tags disabled.
Personally, I like the idea of having keywords meta tags but don't want to go to any effort to generate them. You can do this easily with Yoast's plugin assuming you're using sensible WordPress category and tag names. So I enable Use meta keywords tag, and on SEO → Titles set your Post Meta keywords template to:
I leave all the other Title settings blank, allowing the plugin defaults to do their best.
Under SEO → Indexation, select the checkboxes to disable Date-based archives, Tag archives and Post Formats archives to limit duplicate content on your site and ensure that these are never returned in search results instead of your actual posts. Leave Category archives deselected (i.e. enabled) unless you aren't using categories at all.
Under Archive Settings, select the checkboxes to Disable the date-based archives and Disable post format archives. If your blog is your personal home site so you'll only ever have one author and your home page shows your archive, select Disable the author archives too.
Under SEO → Permalink Settings, select Strip the category base so your category archives appear in the logical place in the URL namespace. If you were previously using WP No Category Base to do this, disable that plugin.
Under SEO → Internal Links you can configure your breadcrumbs, which are supposed to be good but you need to add them to your theme. Can't say I've got around to this on my sites yet.
Under SEO → RSS add your RSS Footer settings to Content to put after each post. This helps give you backlinks from evil content scrapers who repost your RSS feed on their sites. I suggest:
<em>%%POSTLINK%%</em> is a post from <em>%%BLOGLINK%%</em>
Disable your old sitemap plugin, like Google XML Sitemaps.
Delete the files sitemap.xml and sitemap.xml.gz created by your old XML sitemaps plugin from your root directory using Filezilla. If you don't do this, Google will never see the updated sitemap from Yoast's plugin!
Under SEO → XML Sitemap select Check this box to enable XML sitemap functionality, Ping Yahoo! And Ping Ask.com.
Go to SEO → Edit Files Robots.txt and modify your Sitemap line to read like:
If you have manually submitted your old sitemap to Google Webmaster Tools, log in there and delete it. Google and other search engines can find the sitemap automatically from your robots.txt file.
SEO Ultimate has some features that WordPress SEO by Yoast doesn't have. If you use these features you'll need other plugins to compensate:
Deeplink Juggernaught: Install SEO Smart Links Pro and migrate your custom keywords manually.
Rich Snippets: Install GD Star Rating and migrate your ratings manually.
Slug Optimizer: Install Smart Slug (SEO Slugs hasn't been updated in a long time).
Delete whichever plugins you've disabled as you won't be needing them any more.
And you're done!