What slide show or video software is recommended as an alternative to Lr?
Unless you define what you mean by slideshow, it's a more difficult question than you may think. You've also got to say which OS is relevant to you, as slideshow apps are often limited to one OS.
Lightroom does slideshows of course, but part of your definition seems to be that you want to run the slideshow without Lightroom. You do also say you have CC, so you might consider using LrMobile to run a slideshow from your tablet or phone. This method works best when you want to run the slideshow manually, and it's dead easy to get pictures onto the mobile platform and therefore into the slideshow. So depending what you want to do, it may be a question of using what you've got, but just in a different way.
Photodex runs on Windows and does slideshows, but its definition of a slideshow is more like a
standalone multimedia presentation. Is that what you want? You've then got the hassle of getting pictures into it - fine as a one off, but less wonderful if you want to change images.
Foromagico has a good reputation, but it's limited to Mac, like Aperture was.