I have always found the Google Finance site easier to use. Even at the time they trailed in functionality, just getting round and finding information was a lot easier.
until last year Goog finance was trailing heavily after yahoo finance.
I know that the best product doesn't always win, but in this case it seems that users like Yahoo finance much better.
Yahoo! Finance Market Share 52 times Bigger than Google Finance
http://blog.searchenginewatch.com/blog/070319-114123
Perhaps things have changed this year, with the release of the real-time quotes.
Yahoo! Finance was already well established when Google Finance was launched. It's not surprising that it still leads, just as the bloated Yahoo! email service leads Gmail.
I don't want to argue too much about this, but Yahoo search existed way before Google search, yet many users switched eventually to google, and they took the lion share of search.
Also mapquest was a service with lots of users, but google's maps were such a better offering that people switched overnight to it.
You could argue that google hasn't made enough of compelling service for people to bother switching from yahoo finance to it.
As for email, is a totally different thing. I still use hotmail, mainly b/c it happen to be the first email i signed up with, and many of my old friends have that address, so it is not the easiest thing to switch. (I also do have gmail, and a yahoo email account).
While simple financial info lookup, just as search, are less sticky.
Yahoo finance has message boards. They're very sticky -- when I used to visit them in 2001-2002, there were people who had known each other on the boards for years.
>but Yahoo search existed way before Google search
Not to be pedantic, but it didn't - Yahoo didn't have their own search engine for years, only searching of their traditional hierarchical directory and using a 3rd party's search engine, and one of the key reasons Google grew so fast is that they partnered with Yahoo to provide their search results.
For me personally, the sticky point is having to go back and re-enter all my portfolio transactions. Neither site's import/export features are as nice as I'd like.
If you look at how they arrange data around a symbol (e.g. http://finance.google.com/finance?q=KO) it's much better than Yahoo's version.
In particular, tying news updates to price points on the chart (as well as updating prices and volumes on mouse over) is excellent.
Another nice touch is putting the latest price and tick in the html page's title tag, so I can see what's happening even while in another browser tab.