Jaaxy uses a combination of search engine data from the major search engines (Google, Bing and Yahoo) and Long Tail Pro get its search data from Google alone (via the Google Keyword Planner tool). While this seems to be an advantage for Jaaxy, you might only be interested in getting information from the number one search engine in the World: Google.
Basically, Google shows the autocomplete suggestions whenever you start typing anything into Google search box. It is in Google's best interest to show the most relevant keywords in the autocomplete suggestions. Keywords that would help Google to retrieve the most relevant websites and help users find the most relevant content for their search query.
Here’s where this tool’s value really comes in: Keyword Tool has keyword research tools for multiple search engines, not just Google. If you want to do keyword research for YouTube, Bing, Amazon, the App Store, or eBay, they’ve got keyword suggestions (and data) for you. If YouTube videos, for example, are a central part of your marketing strategy, this could easily be worth the money.
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.