Through personal observation, as my walls went from level 8 to 16 while those around me on my team did very limited if any upgrades, walls make almost no difference to your war rank. Offensive upgrades increase it slowly, defensive upgrades more rapidly, and upgrading generals shoots you up the ranks like a rocket.
The total HP of all buildings on your base does impact war weight. But the effect is small enough that it isn't really noticeable.
The total HP of all buildings on your base does impact war weight. But the effect is small enough that it isn't really noticeable.