Spin Rewriter is pretty amazing. There’s an upcoming version 7 launch and I’m hard-pressed to think of anything it more it needs to do. The improvements in v5 and v6 took everything to a new level. So I’m just going to assume in v7 what is truly ‘The Best Spinner’ will just get ‘Best-er!’
That said, one of my biggest wishes is they’d do a full cleanup of Capitalization in their synonym database. For example, too many acronyms like FYI, HDTV, USA, BYOB, SEO, MLM, etc are in lower case. Or, as an Apple computer geek, things like iMac, iPod, iPhone, iPad, MacOS etc. aren’t in proper upper and lower-case. And, far too many substitutions are in ALL CAPS.
Forget sentence structure — NOTHING makes spun content more visually obvious in a split second than these Upper/Lowercase mistakes.
Last thing: Want to test how good ANY spinner really is? Load some well-known document like the Declaration Of Independence, or song lyrics you know by heart, and see whether the substitutions are passable or horrible…