I use it because it supports proper continuous zooming with pinch-to-zoom on a trackpad (exactly like Safari on iOS devices). Chrome does a weird step-by-step increment that seems to involve re-laying out the page at each step. The multi-touch interaction with Safari is just better in general, IMO.
I use Safari because in my experience Chrome is rather buggy on a Mac. Particularly with regard to Spaces. E.g., if I move a Chrome window to a different Space, all of my other Chrome windows will tag along for the ride. It makes using Chrome rather unbearable. Additionally, Safari's interface for managing bookmarks is much nicer.
I just use the standard release of Chrome. I Googled about the problem several times and all I could find out is that some people experience this issue and others don't, and no cure was known. The problem did not go away via numerous upgrades of Chrome, so I eventually gave up.