I spent a couple months this summer researching and looking at decks. How much do you have to spend? 1500-6000 is about the range. The rock bottom price gets you a steel, non expandable deck with plywood decking. 2000ish range gets you a steel deck with the same plywood but now you can pull the sides out to haul 2 sleds or keep them in the width of the truck box when hauling one sled or non at all. 2500-3000 will get you into an aluminum frame. 3500-4000 will get you into more of the options you want. Nicer ramps, Super glides and super clamps are very nice to have. The 4500-6000 range will get you into the full lotus and truck boss. The truck boss is one VERY high quality, well engineered deck. It seals tight to the box sides, is built from extruded aluminum and no welds to crack. Plus the telescoping ramp and expandable sides can be operated with one hand. They work very smooth and don't stick and bind like the ones in the 3000-3500 range do. Truckboss also offers a winch loading option which works great if your in an icy or gravel parking lot, want to load your sled out of your garage or have a 10ft ramp and a lifted truck.
If you go with the lower end of the price range just keep in mind you will be paint rust on the steel decks, fixing cracked welds on the aluminum decks and replacing plywood every couple years. I seen new, unused decks at the dealers that sat outside for a year and already needed the plywood replaced.
This is a general overview, once you start looking you will find a handful of the main builders and a BUNCH of small time guys. Eric