I've tried out the new Romans, and the strategy might work. Well, against noobs, at least.
Don't waste resources on champions. Instead, train a balanced, huge army of citizen soldiers. Cover the usual bases, mass skirmishers as ranged, swords and spears to defend them. Max out, if you can. Leave some room for siege weapons and a Hero of your choice.
Linger on a bit, to build up your stockpile of resources, because you'll likely need it soon. Making a good trade network is advisable, but optional.
As you're preparing to head out, select your Fortress and click on the "Marian Reforms" tech.
Congrats, now you have 200-240 champions eager to smash into the already prepared enemy defensive lines, as your opponent figured out what you're doing 15 minutes ago.
Or, you push out, destroy his army and reduce his towns to rubble. If some of your elite warriors die, replace them with the resources from your stockpile. If the enemy tries to buy time by spreading out, roll out some cavalry to intercept him.
One of these two things should happen