Which is the best keyword research tool?

Here are the top ten keyword research tools that are running in the market of content writing.
Wordtracker
Keyword Discovery
Übersuggest
SEO Book
Wordstream
Keyword Suggestion Tool
Keyword.io
Keyword Eye
Serpstat and undoubtedly Google.
They are now been used by the professional world of content writing and doing their job quite well.

A few good keyword research tools I could find are -

1. Wordtracker
It has a relatively good and cleaner interface. On searching for a keyword, you get the list of 10 best keywords. It has quite a good number of search criteria included within itself. However, you may need to go for Pro version if you want more functionality.

You can access it on http://www.wordtracker.com/

2. SEO Book
You need to register for free. The tool provides you a list of keywords on a daily basis. The keyword search provides results based on Google and Bing trends. The tool lets you export keywords as a CSV file.
Get it on http://tools.seobook.com/keyword-tools/seobook

3. Keyword suggestion tool
It is one of the simplest keyword search tool. After getting the initial keywords, you can dig deeper to find more.
Visit http://keyword-suggestion-tool.com/ for more information.

4. Keyword eye
The free plan lets you search upto 10 keywords per day. It offers customisable keyword query. Download option is also available.
Go to http://www.keywordeye.com/ if you are interested.

5. Google
This should be the ultimate and best choice. It has a number of tools designed for the purpose. Google Trends is one of them. It provides region specific search items. Google AdWords is widely used in the SEO circles. It offers detailed in depth results for your keyword queries.

6. Wordstream
You can get upto 30 searches for free. You will need to sign up for the service for additional functionality. You can reach them at http://www.wordstream.com/keywords

7. Ubersuggest
It provides alphabetical list of keywords based on your search item. The link for the tool is
http://ubersuggest.org/

Most of the keyword tools that offer paid access usually are the one with more data and features. For example, if you want to export larger data in Excel sheet, then not many free tools can let you do that. You can do that with Keyword Planner for Google but data won't be as large as most of other tools.

Here are some of the tools that I have personally used and found them useful.

1. Keywordtool.io : This tool even for free usage gets a lot of "Google suggest" data out. And some portion of that data can be exported. If you regularly scrape the web for keywords then it's worth going premium for this tool.

2. UberSuggest : This tool scrapes data from Google suggestions and Bing Suggest. So they have limited data but like Keywordtool.io they have export options for the data too.

3. SEMRush : They give you access to premium library of tools so they are worth going for if you are small business or enterprise.

4. WordTracker : Free searching over the years have reduced in their offering. Now you have to be premium to use their service. Their dashboard and the data sorting and export features are good.

5. Google Keyword Planner : If you want to do SEO for google then it's fair to say that the data from this tool is more relevant. And all you have to do is open Google account and login to adwords for accessing this tool.

For starters you don't need any other tools than these five mentioned.

With my 2 years of experience, I think I am ready to review best keyword research tools.

SEMRush (Paid) : - If you are seriously concerned about SEO and want to rank then you must give this tool a try. Its charges are way more than normal but it is worth every single penny. It gives you good results about keywords, trends, competitions, backlinks, etc. To increase number of users SEMRush also introduced 30 days free trial period whereas you will have to pay for regular use.

Google Keyword Planner (Free) : - It is good as well compared to other SEO tools available. As it is directly from Google, it regularly updates its database. After SEMRush I would suggest you to for Google Keyword Planner. Same as SEMRush you will get keywords details, trends, etc. but for backlinks and competitor research you will need to rely on other services.

I used many SEO tools but I can say that none of them works as good as SEMRush and Google Keyword Planner.

Regards,
Joy Joon