For your money, Composite can cost up to 3 times, (even more) than treated wood. Composite is prone to mildew and rust staining. Also, to keep the manufacturer's warranty, you will need to use their recommended cleaner. NO pressure washing!! Pressure washing can eject fibers and make the surface even more pourous, making it even harder to clean!
On a budget? Treated, treated and treated.. Framing, floors and rails.