I really like BuzzSumo. While it's not directly an "SEO" tool it's definitely helpful when finding content that is searchable and shareable.
You can type in a topic and it shows you the top shared articles that have been written on it. You can also see who's been sharing it and if there's someone to reach out to for a share/backlink/etc.
Well, for me. I like especially Google Adwords Program, Semrush, Alexa, SEO quake and all in one SEO pack. These really have been a great support for me to work and learn SEO.
Recently, a WordPress Exporting/Importing plugins has been introduced that might made the transfer process easier.
The Fetch as Googlebot tool in Google Webmaster is an effective tool for monitoring the SEO performance of your site. The advantage of this tool is that it can let you quickly detect any issue on the site which prevents it from getting indexed. After it fetched your URL, it will return the statuses of the URL it crawled. There are several status. Complete means Google has successfully crawled the page. Redirected means the submitted URL is redirecting to another site. Not found means the URL is not available for Google to crawl. Not authorized indicates the HTTP 403 error. DNS not found means that you have entered the wrong domain probably due to typos. If it returns blocked in the status, it means that there are some codes in the robots.txt file blocking Google from retrieving the URL. Unreachable robots.txt means Google is not able to reach the robots.txt file. If it returns the status unreachable or temporarily unreachable, it means that the server is taking too long to response to Googlebot request.
Top seo tools is google webmaster and analytic, this best one but you can also use smallseotool, moz, backlinkwatch, ahref, copyscape, siteliner, seo quack and many more tools are available at search engine.