I think Google Adword tool is a best tool for keywords research which is providing good results for any kind of keyword research, the best thing about thsi tool is its is completely free and serving best results to their user. It shows the most relevant keywords and help to show the demand for these keywords in all countries. I also head about the SEM Rush and people are saying that this is also great tool for keyword research but this tool is not a free tool, word tracker is also one more option which we can use. Here we have list of some more keyword research tool.
Free Online Keyword Research Tools:
1. Digital Point’s Keyword Suggestion Tool
2. Google Keyword Tool
3. Niche Bot
4. Overture Keyword Selector Tool
5. Pixel Fast