I don't really know what to vote since:
2 heroes: Well. You won't really be able to do more than two things at the same time, It might be fun if you could attack the other base with more than one hero, and at the same time defend your own base.
Army and Hero: Uh, Would be kinda hard to sneak around and pick your enemies flag with an army running around wouldn't it. How would the army system work. Will the armies respawn after the flag is captured or what? If that's the case it will probebly result in a epic battle everytime one team is trying to get the enemy flag. And the attacking team will also lose nearly all the time since the defending teams strategical position (= lame). Ofcourse you could put defending armies in a big hole or something. But it would look kinda strange. And if the army doesn't respawn it would be even lamer since the army that attack first will be toasted tomato after the first battle. And thus will make it to easy (What resistance are there anyway?) for the other team and run and capture the other teams flag. Or maybe the flag don't respawn and it's just one round?
I really like the idea of two armies running around and fighting epic battles in a jungle (There just have to be nice terrain so you can hide some scout troops behind trees etc.). Explain how the system is going to work and I will carefully put my vote.