Engine Performance: 3.0V, gotta give it to the 1KD-FTV for its superior torque delivery across the rpm band.
Suspension & Driving Comfort: GTV for now. There are some reports saying that the tweaked suspension of the Fortuner puts it on par with the Montero though I wouldn't count on it yet.
Car Features: GTV, you get paddle shifters, 5spd AT, LCD HU.
Real downside with the GTV or any Montero for that matter is the cramped 2nd row bench, barely three people can fit comfortably. The looks are personal but I find that even the first-gen Fortuner ages better than the Montero.
Depends on what you want. The Fortuner should do better on low end grunt or hauling/towing purposes due to the wider torque plateau but the Montero would be better on top end speed and fuel economy. But the Fortuner is still jittery the last time I rode one (2010 2.5D4D) and it was fully loaded.