When I saw Scorpion in his BEST suit('ULTIMATE' suit) using a chained kunai in MSZ while he was brutally kickin my ass, I officially liked the Chain better. Besides it fits him nowadays so can't turn back now even if you wanted the rope back.
The rope fit for the MK1 and 2 scorpion... but for his trilogy suit and onwards; the chain. well, maybe the rope still for MK DA primary costume.
The serpent? no. Sure in the movie it looked cool and all and I guess it might have been the best route to go in order to make scorp appear more of a supernatural freakshow like the others, but for a game, No.
I like the Idea of Scorp(a ninja) having such precision when throwing his chained/roped Kunai(makes him much more of a badass) rather then a serpent with a mind of its own go after it's prey, and still fail...and scorp didnt have the sense to just walk a few steps forward.