Of course Mile Marker's primary distinction is being hydraulically powered vice Warn/Ramsey being electrical. There are plusses and minuses for either method: Hydraulic will run Forever -- but only if, and as long as your engine does too. Electric power doesn't depend on the engine running, but it can't run for very long without a meltdown.
The military could use any winch it wanted for combat vehicles. They use Mile Marker hydraulic -- their testing budget is much bigger than mine, so I figure they picked the one that would best support you when you needed it most. When I've needed it, it's gotten me out a jam. I figure that if the engine isn't running, then winching out my Jeep is only going to make my situation slightly better than it was when I was "stuck" and needed a winch.
Mine is the older single speed model. Now they only sell them with 2 speed gearboxes. The hoses, connections, instructions and technical support have all been 1st rate. I would buy it again in a heartbeat.