Polymaker Nylon Filament 0.75kg Natural CoPA, PolyMide CoPA Warp Free Nylon 3D Printer Filament, Strong & Tough & Heat Resistant

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.