The correct answer is "both," but since not everyone has that sort of time and/or interest.... The Townsend text is, I feel, written with more of a general audience in mind. Smith goes heavier into archaeological digs and looking into things like pottery horizons.

Carrasco's Daily Life isn't really a theology/philosophy book (though Carrasco certainly leans that way). It is more of an intro book which works to fill in the more granular details that the higher level overviews of Townsend and Smith can skimp on. I actually prefer Aguilar-Moreno's Handbook to Life in the Aztec World for this though.

Leon-Portilla is a seminal work, but some of his specific ideas (particularly one the concepts of a singular Ometeotl) have been challenged. You might want to check out James Maffie. I have not gotten a chance to read the book he recently published, but his writings on the subject so far have been superb. He is a philosopher and approaches the subject as such though, so you might want to browse an article or two of his to see if his style makes sense.

There's another book by David Carrasco, City of Sacrifice, which might also interest you. It specifically focuses on the sacrifice, but embeds it within the greater theosophical framework of Aztec culture.