This is one of the best articles on Keyword research tool that I have encountered. However, To add more to this, I just wanna point out a tool (LSI Graph) for an outstanding long tail & semantic keyword research. After the recent Google algorithm, Google is now, however focussing more on context & semantics than keyword alone. What do you think about it?
There is no doubt that there are various keyword research instruments out there, however, many people were often disappointed with many of them because they fail to deliver the expected results. While some of the tools proved to be helpful when you look for specific niche keywords, others were simple failure. You would discover that as time goes on that, it begins to slow down. This affects the efficiency and the speed. This is not the case with Long Tail Pro. It does not only deliver efficient and reliable search results, it does it very fast. You would appreciate the efficiency of the tool when you have watched the demonstration videos and tutorials.
A service like BrightEdge comes with the biggest costs associated, but its SaaS solution for SEO covers many areas inside of a single ecosystem, including the ability to explore keyword data. This may be a benefit for agencies that wish to reduce redundancies across vendors, but eventually, it is likely that the need for a second tool will present itself as talent and effort levels increase inside of your SEO department.

I would like to get LTP but I’ve read that people have some issues according to Keyword Planner and Moz. Do you still recommend this tool? How accurate is it’s data comparing to previous versions? Does Keyword difficulty still works as it should? Maybe it’s better to wait untill some stability of this software? I don’t want to waste money for some tool which doesn’t work properly.

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).