SEMrush
http://www.semrush.com

SEMrush is the best competitive keyword research tool on the market! Regularly scraping over 88 million SERPs and over 40 million domains - from 11 different databases, SEMrush reveals invaluable organic and paid data relative to: rankings, traffic volume, traffic value, CPC stats, domain comparisons, backlinks, and trends.

With SEMrush, you can know just what your competitors are doing - what campaigns they’re running, what their budgets look like, what kind of traffic they generate, and what works for them. Quite simply, it can give you all the ammo you need to effectively compete in a highly competitive online market.