My personal preference is wood. I built my work bench out of 2 by 4s, a thick particle board, and screws. I remember spending less on building it than a cheap bench. The cheap work benches like the ones at Harbor Freight simply didn't feel beefy enough for mounting my bench vice. If you make your own, you can build it to your quality standards and custom needs. You can easily put a piece of sheet metal or rubber matting on top if you want. Wood is relatively easy to work with if you already have a drill/hammer, a circular saw, and some measuring tools. Drilling holes through metal (if bolting parts together) and welding complicates things.