Y'know... when it comes right down to it, there is no one single best anything. If everyone liked the same thing, there'd only be one.
Tell ya what, why don't you pick out a couple niches you think you might like to work in. Then pick out one keyword tool. Any keyword tool, free or paid, just pick one.
Make a keyword list and look for what gets searched for a lot and what the SERPs look like. Then, look at some of the top listed sites. See what they're doing and decide if you can compete. If you can, jump in. If you can't, pick another word, term or niche.
Make your site and see what happens. If it works, rinse and repeat. If it doesn't quit it and move on. That's how I do it and, I'd wager, a lot of others here do too.
In some niches 10,000,000 results is not much competition because the listed sites are so fucked anyones grandma could make a site that can float to the top. In other niches 1 or 2 results is too much competition.
We've been on this topic for a couple days now and I don't believe you're any closer to a decision than when the thread began. It's time to shit or get off the pot.