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Wood
For the look of nature
Wood is a great insulator and keeps the roots of your plants nice and cool. You can plant right in it, or use it as a way to dress up (actually, to hide) homelier cheap pots. If you're looking for longevity remember - the flimsier the wood the shorter its life. Bushel baskets are good for about one season unless strictly used as a cover for a plastic nursery pot and kept off damp ground. Heavier is better - except for your back.
Varnished or sealed wood will last longer - but to won't breathe as well which could cause drainage problems. Luckily, drilling a few holes in the bottom of the container doesn't require a Ph.D. in woodworking. Then there's treated lumber - a definite no-no if you're growing food crops in containers but probably acceptable for ornamentals. You'll have to paint treated lumber containers unless you're fond of arsenic green over beige.