Mostly reputation I suppose. While Wordtracker is not always accurate it is one of the most reliable keyword research tools out there. You should offer full functional free trial to your clients and let current Wordtracker users like myself decide which one is better. I would certainly buy your product if I decide that it is better when my Wordtracker membership expires. But quite frankly if you ask me today which one I would buy, I would rather pay $300 for Wordtracker because: 1- Your site is not professional. 2- Your domain implies that you are another wordtracker wannabe.
Try have a look at AdWatcher.com. It's also a great tool for you to use.. Just need to spend some $ though..
Also you should keep track to the pathways of your site with logfile analysis to find the keywords that send you targeted traffic.
thanks very much for share but i don't know how do i open it ? i used adobe reader but i can't open it
I guess its useless... but you can try google tool.... else give a try to this one...spacky.com it gives quite good results