The only thing Jango and Phasma have in common is that they're helmeted characters with silver armor and weapons meant to sell toys.
Love him or hate him, Jango Fett is actually a character whose action and presence propels the plot and story. He actually has some depth. He's also acts as a bit of fan service to Fett fans. Phasma does none of that and is a throw away character.
So true. Which is really sad for Phasma because the novel set her up to be a very cool, ruthlessly ambitious character with a great backstory. That all got trashed.