Some people think that's Wordai. I don't. I think it's good but certainly not great and to be honest, NOTHING is great or, "hands down the most believable". For the money, I much prefer spinrewriter or the Best Spinner(TBS). For the money you really can not beat TBS and all the things you can do with it.
At the end of the day, my attitude is that "spun content is spun content". IF it is reviewed manually there's a better than average chance that you will get nuked NO MATTER WHAT SPINNER YOU USE. The purpose of a spinner is to save you TIME and MONEY. The idea is to be able to pump stuff out quickly without having to pay someone a bunch of money to write it. Is their risk? Of course, but these days (and it's been this way for awhile) you see people ALL THE TIME complaining about getting deindexed with beautiful hand written content. If you are TRYING to engage your visitors and make them read the content, than that is different. But if all you want to do is get someone to click, spun content STILL works and can continue to work.
So at the end of the day....My advice is to go with TBS as it is a very nice economical option AND it provides a LOT of features and benefits that should fit your needs. I LOVE the ability to do things in bulk with it. Is it perfect? Hell no...but bang for the buck is VERY HIGH in my opinion.
Good luck