I guess you mean Google Planner. The other tools are based on it. Of course you can use GP for free, but it will take you much more time and the usage of other tools to properly evaluate the competition of the keywords.
What abour Google Keyword Suggestion Tool and Google Trends?
you can try semrush or keyword planner.
http://termexplorer.com/Public/ is also good.
Bigups for semrush here too. After the recent google keyword tool change, i've moved, and will never look back. You have to pay for it, buts its comprehensive, and very varied.
Does it let you find keywords based on:
search volume
level of competition
advertiser competition levels
???
semrush is the best.. You can try it..