If you want something that is easy to print, with low warping, great for decorative display models or non-functional prototyping, toys, and cosmetic parts, you should use
PLA (Polylactic Acid). PLA isn't recommended for functional prototypes or end-use parts due to its poor mechanical properties, such as its lower brittleness and low glass transition temperature, meaning it softens easily under heat and consequently is not great for outdoor use.
If you want something a bit more sturdy and strong for functional parts, and also suitable for outdoor use, you should use PETG (Polyethylene Terephthalate Glycol). It prints relatively easily and offers a great balance between strength and ease of use.
If you want something with high strength and high heat resistance for durable functional parts or brackets, you should use ABS (Acrylonitrile Butadiene Styrene). The main downside is that it requires an enclosure to print properly, and it is not suitable for outdoor use since UV exposure degrades the material over time.
If you want something for outdoor use with similar strength, durability, and heat resistance as ABS, you should go with ASA (Acrylonitrile Styrene Acrylate). Like ABS, it also needs an enclosure when printing.
If you need to print something flexible, you should use TPU (Thermoplastic Polyurethane).
