I support Greece, because a Greek Constantinople and Thrace will create clear natural borders for roughly equitable population exchange. (For reference, I'm Chinese-American; have never been to Greece or Turkey)
OTL's population exchanges sent 1.22 million Orthodox Greeks from Turkey to Greece, and 350k Muslims from Greece to Turkey. This was a hugely one-sided exchange favoring Turkey by the absolute numbers, even after the genocidal death of ~500k Greeks and the exclusion of Greeks in Constantinople from the exchange. It built considerable resentment in Greece, led to the effective transfer of significant Greek wealth to Turkish hands (as governments would seize property that could not be transported), and let to the permanent
depopulation of parts of Turkey (as they received far too few Muslims to make up for the lost Greek population.) Many of the multitudes of Greek refugees became radicalized and resentful, leading to a surge in support of the Communist party and the Metaxas regime seized power in response.
A population exchange is essentially inevitable. This was the common period solution to nationalistic disputes. No matter what happened, some people whose ancestors lived in the same place for centuries or millennia would have the misfortune of needing to be uprooted and moved for the crime of being on the wrong side of the borders. IOTL, they were ~80% Greek.
If we set the goals of setting vaguely natural/logical borders (i.e. no indefensible Greek Smyrna enclave) and having roughly equitable population exchange (make the number of people who need to move in each group roughly equal), I'm pretty sure you need to get a Greek Thrace and Constantinople.
Doing some back of the envelope calculations using the 1910 ottoman census in
Wikipedia, Thrace ex-Constantinople (not subject to OTL transfer) -> 365k Greeks transferred iotl who would not be transferred in this proposal. Thrace including Constantinople has 744k Turks. So adjusting the OTL transfer numbers appropriately, we end up with 865k Greeks and 1094k Turks transferred in this proposal- roughly even and much more equitable than OTL. And that's using the ottoman census which is almost certainly biased/inaccurate (I.e. real numbers are likely more equitable.)