I think people's aresenal of keyword research tools are mostly the same: 1) You need a tool to examine search volume, most likely Google Keyword Planner 2) A tool to help you generate more keyword ideas. Tools that work with the search engines' autosuggestions are very popular such as KeywordTool.io and Ubersuggest 3) Then people might add a tool broaden the depth of their data, maybe including something like Google Trends or Moz's Keyword Difficulty tool.
What I really like about them is extensive detail including the keyword difficulty. Ahrefs uses clickstream data to also show how many clicks you will get from the search engine. This is very useful after knowledge graph integration, as many keywords may have huge traffic but they hardly get any clicks from the search engine. Reason being, they get answers directly from the Google search result. Example of one such query is: “birthdate of any celebrity”
The Search Based Keyword Tool is intended for researching keywords within Google’s Adwords network. Unlike the Keyword Tool, the Search based Keyword Tool is based solely on searches from Google.com. This factor causes the search volumes displayed to be considerably lower than the Keyword Tool. Because this tool is intended for paid search keyword research, it contains additional information on Suggested Bid and Ad/Search Share. The Search Based Keyword Tool is seamlessly integrated into the Google Adwords interface and allows marketers to add keywords to their PPC campaigns without having to login to their Adwords Client Center.
In a nutshell, Long Tail Pro helps you quickly find keywords in bulk based on a seed keyword that you input. In addition to returning hundreds of related keywords, the tool also shows search volume (monthly search volume), advertiser bid, number of words, rank value, and my favorite Keyword Competitiveness (helps you judge the competition and keyword difficulty).