Completely agree with this post! I have searched for other free keyword tools but they all did not work as I needed, so I also vote for Google keyword tool!
you can try seo cockpit I say its the cheapest out there but gives you all the features others have Its on my signature.
search on Google also try to find related ad on for mozila fire fox they have have big and huge list s of a ons also you can try DP tools section they have got some best tools