Pressure Treated Decks
If life span and affordability are the most important issues to you then a deck made from pressure treated wood is the way to go. Some brands even have a limited lifetime warranty. The thing to watch out for is that not all pressure treated wood is the same. Some of the less expensive brands are full of moisture and will twist when it dries. Premium boards have fewer knots and a straighter grain. As well they are kiln-dried and have less tendency to warp.
Pressure treated decks are stainable and hard enough to withstand abuse.