Polymaker PolyDissolve S1 PVA Filament, 750g, Water Soluble Support for PLA/TPU/PVB/Nylon 3D Printer Filament

The most engineering-minded consumer brand in this space. Polylite is their everyday PLA, PolyMax adds impact resistance, and PolyWood nails the timber look. They publish data sheets and actually explain what's in their formulations.