I only use two tools - Wordtracker and Google keyword tool. Those are the tools which I find reliable.
All of the keyword tool is nice one But all the Tools shows the suggestion up to 30% of repeated search. The other 70% is one time search so dont worry want keyword Tool u use
Yeah, i like the little rank tracker tool that comes with the seo book toolbar. i've been wanting to find a good online service so that I could track the history of the rankings.
A lot of people like Marketing Samurai, but the est search numbers seem very low. Still good for relative comparisons.
In my opinion, the best keyword tracker is google keyword because it's free and it shows good keywords about your search.