If you want a raised garden bed that will last a lifetime, use stone or brick. As these materials can withstand moisture without rotting like wood.
Wood is the most commonly used material for raised bed gardening. It is simple to use and easy to construct. And if you allow for proper drainage and select a rot-resistant species like Cedar, it could last quite a while.
Galvanized metal can also be used for raised beds. Very simple to make and super durable.