Basing on zone would only excel if it has a major twist from the other types of basing on the other servers. Such as the buyable defenses, yes. Or, instead of attacking a soft spot to take the fort, your squad needs to carry bombs which can be found outside the fort, into the enemy soft spot area and then place it and guard it until it detonates, which then your squad wins over the fort. This would cause strategy revolving around protecting the bomb carrier, deception, and organizing your members to certain tasks. Sounds different and compelling to me :p