I think part of the decision should be considering the settler's origin. The next settler from Bavaria should probably take spot #2. The first settler from Valhalla should go 2 tiles NW of #3 (as Donsig suggested), to allow us more growth. The walking distance for the settler will be the same as if they were going to #3, but the benefits would be greater. Keeping the thought of more growth from better placement in mind, I think the next settler should go to 1 tile SW of #4. Expanding towards the Aztecs is a good idea, and if you count the tiles, this placement fits in well with the Aztec city. We've got some room and some resources, let's use them. We can still use the archer attack on the aztecs while we loosen up on the tight build theory.
EDIT: The city placement numbers I used were from CT's map, not Dis' map.