Godspeed. Or as he is more commonly known. Wally West
Godspeed is so the Rani. Here is why...
Godspeed = Wally West[]
Godspeed is one of the fastest villains the Flash (Barry Allen) has ever faced. Much faster than him. Wally West, the Third Flash is also much faster than Barry so it can obviously be concluded that Godspeed is Wally.
Not Convinced?[]
More evidence is this. Savitar (From the CW) called himself the God of Speed. Obviously he must be Godspeed. And from this website. We can conclude that Savitar is Wally West aka The Rani.
Savitar. Aka Godspeed. Aka Wally West. Aka The Rani