As mentioned, I too find safari tends to scroll more smoothly, especially on image-heavy websites.
One thing that irritates me about Safari is that you cannot set the default page magnification rate, and new tabs don't "remember" this setting. For example, when I open new safari sites on my 27" imac, everything appears so small. I can use command plus to zoom in, but this does not apply to new tabs I open. Quick-fixes like increasing font size or using extensions don't scale properly either.
Conversely, Chrome remembers this default setting, resulting in less frustration overall.
However, I prefer Safari on my macbook air because the tap-to-zoom function lets me make better use of the small screen.
Also, google docs seem to work better on chrome compared to safari. I have had them fail to zoom properly, lag or even crash on safari.
Currently, I am sticking with safari because it seems to work better on my iphone and ipad (for icloud, reading list and bookmark sync). If apple ever gives us the choice to choose our default apps, I can see myself switching over to chrome completely.