My husband works in construction and frequently has to haul scrap materials from the site onto his truck. He owns the Jackson construction-grade wheelbarrow, which has a 6 cubic foot capacity.
This wheelbarrow works really well for him. It is a little on the pricey side, but it comes with a tough steel-reinforced bed that makes it extremely durable. The wheels are mounted with ball bearings, and are pneumatic which makes for really smooth handling. The handles are ergonomically designed, and long enough to give you enough leverage to make even the heaviest loads easy to push. There is a steel crossbar on the leg stabilizers, which adds to the stability.
The tray is supposed to be corrosion-proof, but ours has rusted a bit, so I would probably say it's more corrosion-resistant. It is also very heavy, making it hard to get in and out of the bed of a pickup truck.
If you want a wheelbarrow to do a little yardwork, then you can probably get by with getting a less expensive model. But if you need a hard working wheelbarrow, this model by Jackson is a good bet.