Personally the my favorite place to farm cloth is horde only and its in Twilight highlands. Its the area just to the south east of the obsidian forest. There u will find tanks! What u do is seed of corruption or just aoe dmg each of the engineers around the tank then kill the tank itself. When the tank dies all of the engineers die and u can loot them! They dont fight back even tho they are marked as hostile. So i just dot up each of the tanks make sure to AoE the engineers and BAM lots of cloth greens and tiny treasure chests! Also the respawn is CRAZY fast so u can literally do it all day!