Nexus 7 - higher ppi, NFC, more RAM, quadcore, GPS, $100 less expensive...
More RAM? The highest you can get the Nexus 7 is 16 gigs, the iPad mini
starts at 16 gigs. EDIT: okay, as everyone has stated, this isn't the RAM we're talking about. From what I can see, and I'm sure all the helpful people will correct me if I'm wrong, but we aren't sure what the RAM will be on the iPad mini yet...as Apple doesn't really release that spec. iFixit will tear it down and we'll know, but I have a feeling it will be 1gig, as is the iPhone 5 now. Have a feeling they'll go with this across the board on the new iPad mini and the 4th generation iPad.
Also, comparing the prices of the 16 gig Nexus 7 and the entry level iPad mini is only 80 bucks, not 100 bucks. Sure, only 20 bucks away from a cool 100, but still.
Also, what does a quad-core processor do for you? Can you show me specific examples on the Nexus 7 where this shows it outshines other things? I'm not talking about "oh, it's two more cores so it MUST be better". I'm talking about specific examples. I'd be interested in seeing why this is so important on a tablet.
NFC, meh...kind of neat, but no real practical uses for it yet. Though would be cool to get those little stickers that you can wave your device in front of to change the settings in relation to where you are. Like have a sticker at the door to your house you wave it in front of to turn off bluetooth and the GPS, then one in your car to turn those things on, and turn off WIFI. Things like that. Otherwise...meh.