What is The best article writing tool out there?

Your brain.

Definitely human written content. While I have heard some people who have had excellent luck with some spinners (even some created by people here) for me ... just nothing like the personal touch that comes with writing it myself.

Just my two cents for what it's worth

While the human mind is still best for quality, you are restricted by time. It can take half an hour to properly rewrite an article by hand. Or you could use a spinner, which will nowadays do a pretty good job for you in seconds. If you are starting from scratch, there are a ton of 'research' tools out there that typically scrape google listed sites for stuff on matching your keywords. You then have to rewrite it to avoid copyright, of course. Contentboss has a one click article generation system like this, that spins automatically for you. There are also downloadable ones starting froma couple of bucks.

of course human quality of talent and skills of writing.. maybe you mean best rewriting article tool? sometimes using software tool makes you spam or just only a mess.

Totally agree with the other responses. Your brain is the best tool. I have tried every piece of article writing software, from WSO stuff which are just fields that you fill in like a template to the wizards like Instant Article Wizard and Quick Article Pro. None of these really helped me to write articles faster, mainly because when you use a template type program you still have to use your brain and fitting things into a template is actually a little harder than just writing it yourself (at least for me), and with the wizard programs, all they do is search Google for the keyword phrases and give you the results in a form that can be copied and pasted easily into article form. These produce crap, non-unique articles, what's worse is you are actually plagiarizing if you use the articles in that form. So you must do a lot of rewriting to make them work. UAW and JetSpinner are very good spinners though, but you must get the article ready for these programs by providing different versions of words and paragraphs, which takes a lot of time. If you really hate article writing/re-writing, it's best to just outsource it. Tons of people do it cheaply.

Is there a duplicate content penalty from Google for identical articles or posts. I am hearing a lot about it but can somebody point me to an official Google explanation of this?

I use a combination of my favorite freelance articlewriter and Content FX. With this membership, I can generate articles in 6 different languages research niches and auto post to blogs, article directories and RSS directories.

I am very happy with this service.