A survey from the market research firm of Millward Brown puts Google™ at the top of all global brands in terms of consumer recognition. I have no idea whether the survey is or isn't accurate, though it strikes me as a plausible result.
The interesting thing, though, is this. As those of you who know trademark law know well, a term cannot be a trademark if it has become a "generic" descriptor for goods or services. Lots of previously-trademarked names -- aspirin, cellophane, escalator -- began life as brand names, but over time became "genericized" and lost their trademark protection.
"Google," of course, is used generically all the time -- as in "google this, will you?" or "I googled her this morning and found out that . . ." The most well-recognized brand name in the world is conservatively worth billions of dollars; yet I am not aware of Google, Inc. doing anything to try to stem the genericization of their name. (Xerox, by contrast, with a much less valuable brand name than Google's, spends scads of money taking out advertisements pleading with consumers not to use their name as a generic description of photocopiers or photocopying services). That strikes me as odd, I must say -- perhaps they've decided that there's nothing they can do about that usage? Or that they get plenty of pay-back from having a name that consumers use generically?