In my mind I see the "Nexus" series as the direct competitor to the iPhone, and wish Google would push it hard against it and market the heck out of it. But for some reason that's just not ever happened.
I think unfortunately that's counter-productive to their goal - they don't want to piss of their various partners that are producing other Android phones. Google doesn't care WHAT Android phone you buy, just as long as you own one and therefore are another person using Google apps/seeing Google ads. I do sometimes wonder why they don't do a general Android ad though, one that might say "look at all the cool android phones out there, and look at what they can do."
sigh...I've been getting a little disillusioned with the whole thing.