Here's the deal, they may collect similar info, however, Google knows already far too much about us, and its presence is growing.
A regular user shouldn'tworry too much, but IMs and other pros should.
It gives Google the upper hand in any relationship.
Google keeps the algo secret (and they should), but knows everything about us.
Wait 'til they manage to get a social network going like FB, an OS like Windows and so on, and you'll see!
My vote goes for SC or any other that is not owned by Google (yet).