This is my favourite for searching for non competitive keyword phrases and also getting supporting information. If you understand KEIs (keyword effectiveness indicator) then this is perhaps the best tool around for researching KEIs. There are other tools which have a facility for KEIs but many of them are innaccurate and the result can be a lot of hard work for nothing. You can usually bet that if the owner of a keyword research tool belittles KEIs then they usually can’t get their tool to identify KEI properly. This is not the only area where wordtracker reigns supreme either. If you can’t afford a yearly fee, they let you research for a day at an inexpensive rate. That’s a great reflection of confidence in their own product/service.
Rating = Preferred (especially for KEI research)
You can see it at Wordtracker