You can also ask Long Tail Pro to get extra information like “Global Search Volume” (amount of monthly searches globally for each exact-match search term), “Domain Availability” (to see if exact-match domains are available), “Google Title Competition” and “Bing Title Competition” (this is the “allintitle” search that checks the number of sites that are using the same keyword in the title of their pages).
I recently decided to go with ahrefs after using spyfu for a couple years and trialing secockpit. I was a moz client for awhile too about a year ago. I found spyfu data to be sketchy (or just plain wrong) fairly often, and moz, I don’t know, just didn’t seem like they were really into supporting what I wanted to know. secockpit was achingly slow for a trickle of data. ahrefs isn’t nearly so graph-y as spyfu, but they are so blazing fast and the data is so deep. I enjoy it a great deal, even if it is spendy.
This keyword tool was built on a custom database we have compiled over the past four years. We researched data from the (now defunct) Google Search-Based Keyword Tool and also looked at a few more recent data snapshots to refresh the database and enhance our keyword coverage. Our database contains 28,527,279 keywords representing 13,762,942,253 monthly searches. Our database is primarily composed of English language keywords.
It would be great if you can provide comparative analysis of this tool with Google Keyword Planner. Since you’re using this tool so you can provide best comparison. One differentiation which I understood is that this tool works for yahoo and bing as well whereas Google keyword planner works only for Google but Google being a dominating search engine, gives the highest returns, so only this reason may not be enough to buy it.