What material is best for a raised bed?

After some research, I chose eWood, which is a very strong, dense wood-like material made from recycled plastic. Here's why:

Material	Advantages	Disadvantages
Softwood	Very cheap, attractive	Rots quickly, weak
Treated wood	Cheap, attractive	Leaches toxins into soil, weak
Hardwood	Very attractive, durable	Very expensive
Corrugated iron	Cheap, durable	Unattractive, heats soil, can rust
eWood	Very durable, strong, affordable, resistant to rot, insect damage, UV and moisture, eco-friendly	Moderately expensive

And here's the bed itself, now filled with layers of cardboard, sugar cane mulch, lucerne mulch, tea tree mulch, garden compost, dry leaves, cow manure, mushroom compost and organic compost: