We only really have 4 spots to evaluate
Korea; too vulnerable. Can be taken by Russia without activating mancuhuria. Can be taken by US during a SZ6 cross. An airbase is better than a fac.
Manchuria; this is good for defeating Russia, defending against Russia (and the US if it comes that way), and attacking Mongolia, but that’s not really optimal because there are no strategic objectives up here, just defensive and attritional war.
Kiangsu/Shantung; these two are pretty much the same. this is the vanilla choice because its safe and you can do it early. However, the very puzzle-piece like arrangement of China means that you are an additional turn north (with armor) and usually 1 more space than that out of position to attack india or the areas around it. Access to SZ 19 is ambivalent at best.
French Indo China; I never saw this as a good position in the past, and its not if you J3 or J4. However J1 openers are more popular now, and you don’t lose the bonus NO (American Oil) if you are at war anyway, you already lost it. Also, you cant place here T1, so you have to save up some $$ and wait.
However, it is a massively better choice than the others, the discussions on the board have convinced me of this. You are closer to INdia. Sz 36 is not a great place to put stuff but if you have a naval or air base on Kwangsi (very popular) it can protect/help that SZ. You are much closer to india here. Even with placing planes and strat bombers, they are right at the front.
If you place in any of the first four areas, it gives your strat away as well; it would seem that you are going to fight china and eventually invade india. If you have any other strategy, placing the MIC early and dropping 18 worth of armor each turn will leave you with too little money to execute other plans or supplement your navy.
You need transports anyways, more than 3, so typically 5 or 6. You cant buy all of it (though MIC + tran + tran is perfectly fine = 26, you wont be able to afford to fill this stuff with infantry, much less better stuff).