I say its completely up to your preferences, but a good war setup would be lowlands all t4 balanced attack buildings, then on highlands, something like 5 spy def towers, 5 def towers and the rest spy buildings
Tower build, and then t5 attack. So 20 spy defense towers in the lowlands, 4 SoS in the lowlands, 1 castle. Then 25 balanced troop T5 buildings in the highlands. Or you can have a volary or two or a few highland spy defense towers if you want even more spy defense.