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”
These are usually single-word keywords with insane amounts of search volume and competition (for example, “insurance” or “vitamins”). Because searcher intent is all over the place (someone searching for “insurance” might be looking for a car insurance quote, a list of life insurance companies or a definition of the word), Head Terms usually don’t convert very well.
So which tool should you use? The simple answer is ALL of them!! If the data from several tools suggests that a keyword may be a good keyword to target, than you should feel fairly confident that it is. If your results appear to be contradicting one another for a particular keyword, then you may want to be hesitant in including that keyword in your selection. SEO professionals should never rely on one resource for research. No one tool is going to be 100% accurate and you stand the best chance at making the correct strategic decisions by using a variety of sources.
Long Tail Pro is a keyword research tool that helps you quickly find low competition keywords for your website. In particular, the tool is built for people doing SEO (search engine optimization) as opposed to people doing paid ads (Google Adwords PPC). I'm sure there are some advertisers that use the tool for paid ad keyword research, but the tool was built for SEO keyword research.