I put a lot of thought into this at one point -- as there are some canonical Orthodox who come pretty close to basically saying the OCA isn't actually Orthodox, yet here I am anyway -- and I have to conclude that there really is no single objective test for whether a given parish or group of parishes is canonical. There was a time when (I believe, from reading) that Arians had the upper hand over the Orthodox, and anyone who converted to Christianity and asked "but what about those little churches over there, the ones who insist that Jesus is coeternal with the Father? They're on the outs with the empire and are probably schismatic" would probably have understandably, and wrongly, concluded that the Arians were the real deal. Is it possible that ONE tiny sect could become the one that's actually held onto the true faith, while the rest of the world falls into apostasy? I don't think it's impossible.
Whenever a schism occurs, the two sides always step back and point at each other as being the schismatics. That's obvious. Historically, whichever side has the backing of whichever state controls that part of the church usually wins, at least for a while. Iconoclasm had a temporary triumph that way. Luther's ideas would never have solidified into a new type of church without the backing of the German princes, who didn't want Rome taking any more of their land or taxes.
Rome offers a tidy answer -- you're in or you're out -- depending on whether you're in communion with the Pope of Rome. And of course you can find some really whacky sects and churches around the world that are in communion with Rome, but appear to have deviated almost entirely from any semblance to historic Catholicism. And there are "One True Honest We-Really-Mean-It Catholic Church" sects that are clearly in schism, but would appear to be far closer to Catholic tradition (at least, medieval Catholic tradition) than most modern American parishes, but they're out.
Protestants often try to solve it by appealing to "the Bible." Just read the Bible and you'll see whether Denomination X is legit! And we Orthodox rightly point out the flaw in that logic. But then many Orthodox will offer precisely the same answer themselves, saying things like "Whichever jurisdiction is closer to the Fathers." Which Fathers? Which interpretation of the Fathers? And if the individual has to make that call, then hasn't the individual basically just become a Protestant, putting his/her own interpretation of Scripture and Tradition above that of the True Church? (Which, of course, he/she can't identify by any other means...)
Catholics point that out, to say "See what chaos happens when you don't have a Pope! Come home! Follow the Pope!" and then thousands leave after learning of decades (or longer) of cover ups and horrific sexual abuse scandals around the world -- asking "Would the True Church have been blind to *that*???"
But those are my philosophical ramblings. I spent years trying to find what I believed to be the true church of the apostles. I found it in Orthodoxy -- after many years of MY own reading, MY own experience, and MY own reasoning -- which any Protestant will point out is not dissimilar from their own journeys into Lutheranism/Pentecostalism/what-have-you. For that reason I cannot smack down someone else who has arrived at a different terminus than I have. What about "Oriental" Orthodoxy? Goodness, I've barely read about it and there's only one church nearby and they mainly speak Egyptian. I can't give a logical, reasoned answer to why I'm not that, instead of this.
As to "which paris or jurisdiction is actually considered canonical with respect to established, global Eastern Orthodoxy..." Until the hot mess that just developed between Russia and Constantinople, communion with the latter was kind of a test. It's more like "look around and see what the overall temperature is in the Orthodox room" I guess. I personally look heavily at the attitudes of those who lead a parish. If you find bitterness, resentment, unwillingness to listen, and a quickness to rain fire and brimstone down upon the heads of any who disagree -- combined with a name like "The One True Only Church Of Non-Heretical Orthodox With Beards" -- then it isn't the real church. They will know we are Christians by our love.
I've met plenty who observe the Old Calendar, and do so out of love. I've met others who define their lives around it, are obsessed with it, and think the Devil and all others who observe the Gregorian Calendar will burn in the enteral pit -- and they're frankly just mean, bitter people. Big difference.
Did I actually make a point? I can't tell sometimes