I've only used micro niche finder, traffic travis, and occasionally the free keyword tool at wordtracker. These are great for newbies getting into the keyword game. I think marketsamurai may be a little too advanced for newbies.
I'm launching a keyword discovery module tomorrow (finishing it up tonight) that should round out the toolset much more. You'll be able to access it with a trial account, so when it launches I'll announce it in my thread and you guys can check it out.
A lot depends on how much you are willing to pay. Market Samurai is very good but not cheap. If you are on a tight budget then Micro Niche Finder is a good place to start
+1 to this. I'm on my second month of subscription now. Everything that took me about half an hour per keyword (Lots of information there) now takes a few seconds to input the keyword. It's replaced everything else.