light tanks

Depending on doctrine and planned usage, but usually they are replaced with AC (armored car) for zerg strats with planes, and by med tanks/ mot inf/AC with fast stacks strat. OK early game unit though

I use them heavily as pan asian, in the early game only as axis, very rarely as comitern, and never as allies.

Pan Asian they're pretty insane. I have the elite level and I abused it in a game, I baited my opponent into invading me with 30-stacks of railguns+AC+infantry, I waited for him to cross the plains and attacked him there. With +70% terrain bonus, the light tanks destroyed a 30-stack in a single shot.

In general I don't use light tanks, if you want an AC-like unit but offensive then Mot Infantry is great, especially as Axis. Mot infantry is crazy fast with good scouting and also stronger in cities (which is the best terrain bonus for conquering). Only problem with mot infantry is the food cost, as you need much food for Recruiting Stations alot of the time.

So I'd say light tanks good for Pan Asian. Other than that, generally better to use AC for scouting, looping around and taking all the weak territory; and infantry backed by artillery for slowly eating the enemy armies alive.

Agree with @Hornetkeeper and @overnor light tanks are rather OP in Pan Asian. When i was German Empire, a very experienced Nationalist China defeated my rather strong units with the fast light tanks, they crossed so much territory within an hour. Even planes stood no chance. Other than Pan Asia, armored car is used more often