that really depends on your style of playing. My favorite doctrine is Allies, since they have a research and production time reduction, which really helps you make units fast. There is a 10% speed loss, but it’s only 10z and it doesn’t really affect the game much, espciecallly when you have 30% more units.

if you like planes you should use allies, cause they have good tac. bombers. Allies also has good SP artillery. Allies doesn’t have the best tanks...but they aren’t that bad either. I usually just use light or medium tanks. Also if you are going to use allies try to make commandos, they are stealthy and strong.

Soviet doctrine is good for reckless strategies. You can afford to lose more units. That is kind of a relief IMO. The production bonus alsomeans you can largely ignore upgrading. Just build new stuff.