Two masters of luck manipulation from different but similar continuums are pitted against each other. Was very surprised when this thread wasn't created long ago.
Good question, and nice matchup using characters we (unfortunately) don’t often see.
As Riv said, easy answer is LongShot.
While Major Disaster seems to have serious powers (change probabilities to bring asteroids down from orbit, create earthquakes and who knows what else), LongShot’s powers would likely make those backfire on him.
Major Disaster’s powers are primarily offensive.
LongShot’s are more defensive, although that can result in interesting effects since to make them offensive he only need to put himself in the mix of things and stuff will happen.
Longshot easily.
Disaster can only bend probability to make bad things happen while Longshot also makes probability work to protect him.
Ah la Thor appears out of no where to catch him mid fall, a hellicarrier stoos falling due to gravity as its about to hit him, magnetos power stops working vs him.
LS's luck would mean Disasters power wont work when he tries to attack