If you need keyword suggestions and search volumes - try Google Keyword Planner, it's free If you need to estimate competition, you could use markets samurai
I would recommend Advanced Web Ranking for the keyword research tool - it has integrated multiple keyword tools, which you can use to get a bunch of keyword suggestions, starting from the primary keywords that define your business - http://www.advancedwebranking.com/keyword-research.html. It has a free 30-day trial and no feature limitations.
Well, keywords research is much a matter of smart analysis. Good tool can't help you any inch when you don't know science behind keywords. For the sake of answer, Google Adword's keyword planner is by far most comprehensive and easy to use tool. HTH
If you're wanting to do seo for offline clients then Long Tail Pro would be the best way to go, however if your wanting to seo your own sites or affiliate sites then Keyword Canine is the best way to go. With this said, it is more a case of what you prefer as many will do the job if you're knowledgeable about what your looking for.
Hey If you're ready to invest try out with Longtail pro which I feel good with this keyword tool else you can move with free Google adwords keyword tool
No sir, if you have Google Keyword Planner, why you are looking for some other tools for your keyword selection.
You can get all of the keyword info you need to use a combination of Keyword Planner (which is really much better than the old tool for local keyword research) and a niche site like SEO Majestic and tools like SEO Spyglass for the competition details (all free tools). My Opinion Google Keyword Planner is most beneficial tool for keywords research
Lately I've been using a real trick method for finding some real gems...do you have Scrapebox? Use the keyword scraper to find 100's - even 1000's of related keywords. It's as simple as plugging in your keyword, selecting keyword scraper, select the source you want to scrape from (Google Suggest, Youtube, Amazon, Bing, Yahoo, etc.) and run the scraper. Once finished, remove the dupes, transfer your results to the left, and run the search again using your remaining keywords. You can keep repeating this process until you have a good amount of keywords. Then, I head on over to GKP and plug'em all in. Takes a little patience, but worth the effort - you'll find a few money keywords that (for some reason) other keyword tools just can't seem to find. If you don't have scrapebox, you can get it here cheaper than anywhere else (not an affiliate link): $40 off Scrapebox BHW
The keyword tool that really work for best for me is the Google Adwords keyword tool . you can find all the keywords for your sites and all the daily and monthly searches for them.
I also prefer Google keyword planner tool. I usually follow these steps for keyword research: First identify keywords on the basis of clients business services. Track their competitors keywords. Use google suggestions for more keywords idea. Next to use ubbersuggest.org to get several combinations of service related keywords. next to put all selected keywords in Google keyword Planner tool. It works fine for me to find relevant keywords for client's website.