I personally can't stand the standard thin pads... Wearing socks I have no grip, barefoot my feet sometimes stick to the pad picking the pad up with it when I pick up my food. Wearing shoes will break the pad in no time flat. It slides around on the floor and when combined with the barefoot issue will cause the pad to spin under my feed when doing multiple jump maneuvers or bunch up when doing fast steps. Not to mention there is no way to tell which button is which so quite frequently I'll get off a little bit and none of my steps will register until I look down an realize the pad has shifted.
The arcade is the best because you can use rubber shoes for good grip and stability, the buttons have awesome feedback with the pressure sensors they use, obviously no problems with bunching up or sliding and the buttons are recessed so you know where you are on the pad without looking.
Back in the DC days I ductaped 2 pads side by side to a giant piece of plywood and it was pretty damn good. I recently bought a set of "thick" pads for my Xbox and they're probably the best pads you can get get at a reasonable price.
They're like the thin pads but they have a few mm thick piece of plastic under each one of the buttons and they zip open so you can insert a 1" thick piece of foam, they also include little felt/rubber feet that grip to the floor or carpet and keep it from sliding about. I don't have nearly any of t he problems I did with the thin pads, I can tell where my feet are it sometimes moves slightly but not nearly enough to bother me, it never bunches up and I don't have to worry about the plastic sticking to my feet.
The arcade is better by a long shot but the $35 shipped I paid for these two pads was money well spent, especially considering you'd probably get and experience only slightly better with an expensive metal pad... and still not as good as the arcade.
The problem is... I wont be able to use these pads on the Xbox 360, and there's a really good possibility there wont ever be similar ones made for the 360.
It might prompt me to make my own arcade replica pads. I'd considered on many occasions to ask my former boss (who owns the arcade I used to work at) to let me take apart a real DDR machine one night and create completely schematics for the real pads so I could reverse engineer them. The real pressure sensors can be purchased for about $80 per pad, you can buy the real acrylic buttons too, the frame is wood, with a metal surrounding (which you could make with a sheet metal bender), and you would probably want to steal the electronics out of a consumer grade pad (so it registers on the console as a pad rather then a controller)... I think you could build an exact replica for about $300