As Jeremiah stats, the Patrol based Armada is very much truck-based, however they gave the US models extremely soft spring rates. I had one for 2 weeks for work and was happy to turn it back in. It reminded me of 90's Cadillacs, the way it floated in the freeway. I don't think it would be a good platform for towing.
The Expedition right now is the best overall towing package, and has more payload available than the Armada, but more important the 3.5L EcoBoost is just a nicer motor for towing, since it makes so much low-end torque. The Armada makes really good power, but only had high RPMs. It gets loud when you get on it.