Nexus 7 destroys the Swindle Fire. I bought the boys one for xmas and it's an awesome device. That said, there may be a rev 2 of it released this summer with microSD slot and hdmi output. I bought the 32GB version and am perfectly satisfied with it as-is. I may buy another one this summer when the new verion drops, it will be the ultimate tablet if they add those 2 things.
My mom has a kinde fire, btw... She is envious of the Nexus 7 and wishes she got one of those instead. Kindle store is available for android if that matters at all to you.
Edit: If you have a droid handset with NFC capability, you can transfer/sync anything between the Nexus 7 and your phone. My crappy Stratosphere doesn't have NFC, but my next phone certainly will. Amazon store is available in google play, too. I can't think of a single good reason to even consider a kindle over it.
I just got kicked out of McDonalds...