1) Ahrefs to quickly see “the big picture” when it comes to any keyword I'm researching. I can instantly see the top holders in the SERPs. I then immediately take the top holders list and go check out their sites. I need to make sure I can beat them content-wise, otherwise I will search for another keyword to try and rank for, or perhaps go down the long-tail route. The Ahrefs tool and data quality get better and better every year. It's one of my favorite tools.
Once I have a list of phrases, rankings, and volumes from these tools, I'll look to internal tools (maybe Excel, Access, or another database) to organize, classify, and forecast opportunity. This is where I'll estimate a competitor's traffic based on volume & position CTR, set goals for a target position, and estimate traffic based off that position's CTR and keyword volume.

We’re not here to dwell on the good and the bad of Google’s decision. I personally am elated that this debate has brought the crucial SEO function of Keyword Research into the limelight once again. There’s more to it than taking the first 10 results from the Google Keyword Tool and scattering them left, right and center in your content. Savvy keyword research is what separates strategists from headless chickens.

To get started with the Free Keyword Tool, just enter a keyword or search term into the relevant field. If you want to conduct competitive intelligence research into your competitors' keyword data, you can also enter the URL of a specific webpage to view keyword data for that page. You can also enter your industry and country to see even more accurate results; it's not unusual for the cost-per-click and other metrics to differ widely from one country to another, even for advertisers bidding on the same keywords in the same industry. 
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).