Fist will shut down any roaming super, has a bigger range, and can jump towards the enemies. Landfall has a small radius, and barely does enough damage to kill a normal person if you're right on top of them. Fist also travels up, higher than possible to jump over, landfall, I'm not sure on since I'm usually above them if it's going to kill someone. Landfall will blind you though, giving us time to actually kill you with our super. But probably the biggest issue with Landfall, is that you either have to use an exotic for it, or you give up blink which is a far far far better perk.