I took the liberty of making a tentative dot map of the revealed land:
SB's proximity provides a bit of conundrum and certainly concern about settling our immediate area. RNG will be a factor. Will he settle land away from us or right in our faces? On this difficulty level we may be ok, but on IMM plus it can be very difficulty to get a city out to beat the AI to prime spots when they are this close.
Anyway, I chose site A as I played around with several sites. This site best uses all the land and closes the gap with City B, if we in fact get that city too. 1W of that site will cause a border war which we don't want. 1SW is an option but will leave a gap of land as we can't settle City B any further south without a) losing cow b) border friction. City B looks like a great production city.
Site A could just go on the PH 1 south, but again this creates a gap and we lose the green tiles in the middel. The grass silk is out of play either way and will be taken by SB anyway, although later we will gain culture of course.
Another argument, is maybe we just want to settle more aggressively in the AIs face and I can understand that, but it will be dangerous in the early game to do so. SB has been known to attack weak humans early game.
Site Y1 or Y2 seems obvious. Y1 has a lot of overlap with the cap though and we will arleady have a bit of that from other cities. Presence of seafood will be a factor as well once we explore the area. Y1 gets the wine, but wine could be picked up by a city due north .
Same for Site X. This is more of a question city we can settle later and seafood would adjust it. It has a lot of overlap with the Cap where it is, but makes best use of the land. Seafood down south would adjust the site though.
Note: I labeled these 2 cities X and Y as they may not be C or D. In other words we may find key sites that need to be settled much sooner than these 2.
The key right now though is to get Site A up asap and possibly rush out Site B as well to secure a good amount of neighboring land. We will need to be chop heavy and probably want 2 workers asap as well. Marble can get up quickly for an Oracle>CS push.
edit: X-post with Rolo. I think BW is crucial now to get out settlers/workers asap. Hunting would be good pre-AH with ivory. Then push on to Masonry>PH