I would suggest Spin ReWriter, personally.
It's web based so you aren't messing around with installing programs and dealing with strict licenses that are limited to a certain number of machines, as well as your files all being saved locally.
To manually spin an article, all you do is paste in your article, and let it analyze it for a few seconds, then it takes you to a new screen with your article, and about 75% or so of the words and phrases in it highlighted, meaning it has some suggested synonyms or phrases you can swap them out for. All you do is select the first word/phrase, and the suggested synonym list pops up and you pick which ones you like, then tap the right arrow to move to the next word/phrase, and so forth. By the time you make it through the whole article, your final "spintax" version of it will be so unique it will pass through Copyscape with a breeze *and* still look like it was written by a human, and be perfectly readable.
The bottom line is you really need to put the initial time and effort up front to create a master "spintax" version of an article. Once you do that, you can generate hundreds of perfectly readable variations of it in an instant. And this is without even using any of the other bells & whistles in Spin ReWriter, such as shuffling sentences and paragraphs - I don't do any of that (personally I think that just makes a mess of the logical flow of the article).
Yes, Spin ReWriter also has the ability to completely automate the whole spinning process too, but I did not like the final output. It's leaps and bounds better than it's competition, with the exception of WordAI, but it's still not "great". You can still tell it was spun. Even WordAI's completely automated output, while the best of the bunch imo, still looks "spun".
The reason I ranked Spin ReWriter over WordAI were a few things. It's much cheaper at $77 per year (after promotional discounts) than WordAI, which is over $300 per year. It's manual spinning workflow is much better - more intuitive and better overall functionality. The other thing, was as expensive as WordAI is, the whole UI is really really basic. I'm talking one form field to enter in your article, and maybe a handful of buttons/options. It's too automated, and it's cumbersome to try and clean up it's output within the interface or tweak the spintax to make it output better spun articles.
