Entirely depends on the gamemode and the factions involved.
Random plains / steppe for battle mode, especially factions that are good for infantry formations.
For duels, ruins of course. Not big, with obvious duelling places, easy to find eachother.
If I feel like doing some CQC I'll get myself a short bow or crossbow and jump into village.
Nord vs Rhodok is often quite fun on Nord town, though it, like village, can end up in a camp fest sadly.
I totally dislike port assault though.
Never played scene 6, what does it look like?