This keyword research tool is effective, automatically providing you with keyword suggestions that other sites haven’t necessarily turned up (which it’s intended to do), along with their search volume, CPC, and Adwords competition. In order to get any actual information about the keywords, though, you need to upgrade to Keyword Tool Pro (which is a little misleading on the site copy). This plan is $88 a month, and if you’re just doing keyword research for Google, I’d recommend choosing one of the other tools for the price.
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.