I like wood, hate the noise of metal. Wood works well if you do it right. I'm going on 6 years with my top, and although it shows a few dents/burns/wear, it's nothing big.
If I get a dent in it, I have a can of varnish in my box, and at the end of the night, I just put some varnish in it, and do that every night until the dent gets filled in. That's pretty rare, though.
I have about $200 in my setup (cabinet included), including all wood, hinges, handles, plexiglass, two outlets, 50' of 10-2 cord and a twist-lock end.
The top is a 36" solid core oak entrance door I got at an auction for $15 or so. That was just enough for me to be able to rip it to 30" and get rid of the keyhole. The routered trim pieces on the edge keep things from rolling off, I would never go back to a flat top, especially if you roll your box around.
I sand it (usually not to bare wood) and put 8-10 coats of spar varnish on it every 2-3 years.
It's sturdy enough to spin the 2500 lb box in circles with the brakes locked while reefing on things in the vise.
The top isn't attached, never had a reason too. I cut grooves in the back of it to drop on the lip of the box. I figure it'll be good for around 15 years total, at which point I'll get another door, knock the trim pieces of this and put it on that one, and go again.