Polymaker Carbon Fiber PLA Filament, Carbon Fiber Reinforced 3D Printer PLA Filament 1kg - PolyLite Carbon Fiber 3D Printing PLA Filament Strong & Easy to Print & Matte PLA-CF

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.