what's your favourite doctrine

I like Comintern since they scale safely, although their early game is kinda slow. Late game they're probably the best doctrine. Their -10% damage seems to balance their stronger artillery but you will feel their doctrine buffs later on.

Allies also slow, and if enemy has anti air you gonna struggle.
Havent tried it but it seems like Comintern counters them. Allies rely on mechanized troops and Comintern has strong artillery which handles them well and counters Allies' SP artillery. If you build enough interceptors to defend Allies' Tactical Bombers you are good to go. Also you outscale them if you focus on limited amount of troops so you arent outleveled.
Pan-asians also counter them with huge speed difference and stronger interceptors.
So it seems to be kinda lame doctrine, which is quite safe and slow and can adapt to others but not really good in anything.

Axis has nice units buffs and their early rush is quite strong especially if you border any other doctrine. If you joined a game a couple hours ahead of your opponent you can rush him before he has a chance to react. You can get one city safely with big stack and play on defense untill your opponent leaves the game.
I feel like they fall off later on though.

Pan-asians are fun if you are going to stay active all day long (maybe night too) and dominate early game. Good thing is that this doctrine doesnt border axis anywhere so you wont die at first day. But they do border Allies so you can abuse that.
But playing that doctrine you can feel pressure to keep conquering and being the first one to attack or you will end up with big stack going at you with no way of stopping it. If you are even to others then you are behind. You can always bunker up in Australia though. No one will try to even touch you because they are probably invested in land troops and wont like to provoke naval war :D.

It can be very situational, but I enjoy Pan-Asian the most. Any other doctrine feels slow. My favorite unit, Heavy Tanks doesn't go well with Pan-Asian doctrine though. There are many maps where Pan-Asian isn't a choice however.

If there is an extended peace period Allies are definitely good, as they research better and upgrade better than other doctrines. Good for less active players as well, and they have the best air force.

On smaller land maps, or perhaps Antarctica map, I like Axis for Rail guns and starting unit strength. Those Labs on the Antarctica map provide lots of resources for Axis as well. Axis Railguns can be oppressive to play against if there isn't a lot of ground to cover on mostly land maps. Stacks of 5-10 Railguns, 5-10 anti air with a couple motorized are very difficult to deal with unless you can trap the railguns into a close combat somehow.

Comintern does well on larger maps, as armies get huge their upkeep reduction shines. I think their SPRA is amazing, and between its speed and unarmored attack it can take out half the enemy army in 4-5 hours while they are asleep.