If you are on a budget or this is your first time developing a site, then I recommend using adwords by Google. This is a great keyword tool and it is free. If you have a little bit to spend on this project, then wordtracker is a great tool to use. Now if you have a larger budget and want the best in keyword tools, then go with Hubspot. Hubspot has website grading tools along with many ways to generate keywords, track your keyword success and your competition. These kind of tools are for the seriously dedicated seo specialists.