There aren't a lot of good mac screensavers out there so I thought I'd share my setup:
I am using websaver and a modified version of designerboard.co
Why modified? - designerboard loads a lot of images and gifs in the background (it is meant to let you scroll through it continuously) and when left on for hours it would have stressed your processor. This version is limited to only the first 30 images (which is how many can fit on my 27" screen). Navigation is also removed.
Since this is for personal use, you should be able to customise your own (reduce number of images on smaller screens, disable gifs altogether to save even more CPU%, etc).
Any other website should also work.