Hey Mork,
Each Complex can only mobilize a maximum number of units equal to the income value of the territory it occupies. Therefore, you can only mobilize 3 units per turn in India, or 8 in the United Kingdom, for that matter.
Also, you say you have 3AA, but only 1 AA in any terrotory is actually active… having more than one of them in a territory does not increase the defensive value of your antiarcraft system at all.
That being said, India is a good solid bet, Australia can be fun if you give it some early US support, Anglo-Egypt will inspire some extremely fierce fighting for Africa, and South Africa is a bit slow to get in the game but is okay once the train of troops comes into contact with the enemy. I have never placed a Complex in Canada because it seems too simliar to the UK in terms of placement flexibility.
All other original UK territories are Value:1 and therefore a waste to place a Complex on, in my opinion.
India can be reinforced with the Russian armour from Caucasus in R1, if you can spare it. Both Russian fighters can also get there in R1, but that means that both of them have the option to attack only West Russia in R1, by virtue of their movement limitations.
~Josh