Like in real life, strategy in the game is ever evolving. Once upon a time the best players and premades would tend to aim for inner core starts so that they could expand outward more easily than expanding inward. Noobs and weaker players would prefer the outer core or rim because they figured it was easier, competition was less intense, and you started off higher villages. Eventually noobs started to jump on inner core start, thinking that as long as they started first they've have a good chance of achieving good rankings. So lately, many of the strongest players and premades aim for the outer core to take advantage of better farming, avoid tough competition from other premades starting outside of them and attempting to expand inward (especially since nowadays the outer rim tends to get a faster overall upstart than the core), and to take advantage of easier overall expansion in any given direction.
I think that inner core is a more ideal start at this point in time for people not in a premade and/or are planning to wait for a good tribe to emerge before they join one, because outer core start will leave you open to being cooperatively farmed. But for premades, outer core seems to be ideal. With time, strategies will continue to evolve as people continue to adapt and find new ways to seek out advantages over whatever trends are popular at the time.