Here I will try to "rate" - on a complete subjective basic - some Theme/style Plugins for Confluence 

...

Conclusion (very subjective after a short test): Problably an excellent product, but as with Zen, be prepared to take on a time-consuming task to design Your style(s). As a private focusing on content rather than nitty gritty design, I kind of "resigned" on the plugin.

Brikit ThemePress

To be honest, I never got it right - spent some 1/2 hour figuring it out. A minus could be that my other Theme plugins fucked it up a bit - but I never got the idea in the Layout and building block pages - and I do hate plugins that twist standard Confluence things and change their behavior - suddenly the "Edit" button did it a bit different and a new menu item on the Tools apeared: Edit entire page - Followed by a warning about this was only for certain procedues as copy page etc...

The videos seems nice and the documentation appears well at first sight, but I never got it.... 

Overall conclusion

No theme can be branded as a winner, for that the themes are way to different, and each coveres a part of what the need You may have.

Zen Foundation and Adaptavist ThemeBuilder (and perhaps Brikit Theme Press) is for sure the leading products if You want to go all the way, whereas Enterprise Theme in general is quite "portal"/Internet aming. RefinedWiki is easiest for making a quick and nice look in overall, and with a Designer for making Your own themes, something the users of Enterprise Theme may miss after a while.