The snatch grip deadlift from a 4-inch platform. If you think about it, the sumo deadlift, IMO the easiest way to DL, shortens the range of motion. You have a wide foot stance, narrow grip, and you take your shoes off (not specific to the sumo, but a lot of guys do it), all to be really low in relation to the bar. The snatch grip from a 4 inch platform is basically the exact opposite. It's gotta be the hardest way to deadlift. You're dropped down into basically an ATG squat, and the resistance starts from rock bottom. I currently haven't even pulled 225 in this lift yet.