Looking at both spinner’s spun articles, they both seem to generate spun content that looks pretty good. Both have some grammar issues I would correct if I was posting it on a high tier 1 site, but overall SpinnerChief produced better content. Not sure if WordAi is being overly aggressive on the spins at the cost of quality. This test is very hard to call. If you go by raw numbers, SpinnerChief won. I want to leave this up to you to decide which one won. Winner none – draw!
There are many people who still prefer rewriting their articles by hand. They are used to write sentence after sentence and rephrase their content to ensure the quality of writing. Although it is the safest approach but it can take hours or days to complete a task. On the other hand, there also exist people who are either too lazy to rewrite their content or they understand the importance of time and hence, they look for an article spinner tool or paraphrasing tool.
Imo it is not possible for google to detect properly spun content, it is not worth computing power it requires. They can do this using ngrams for example, but it is uses a lot of queries. And for example article spinner I coded beats this algo, so google cant detect that the content is spun. Manual spinning is also good but it takes more than 30 minutes per article.