I would say google nexus 7 over an Amazon Kindle Fire. The Amazon offering is good if you want in on the Amazon eco system, thats the ebooks, music, movies from lovefilm etc, but it runs a heavily stripped and modified version of android. Google too offer books, movies, music too from their store, as well as the entire collection of apps on google play store.
You will have no problem running Netflix, spotify and facebook on the nexus as well as very good web browsing.
What is your max budget by the way? and would you consider a 10 inch tab or just the 7 incher?