Well, it's either RPM or Mystic Force, lol.
But, yeah, has to be RPM. It was better written, introduced the new rangers better (specifically Solaris Knight- White & Wolf Warrior were done on par with RPM Gold & Silver) and had a slightly better written finale, which boots out Mystic Force's larger universe & scope & it's closer knitted story.
Overdrive & Samurai was/ is crap. Jungle Fury was just underdeveloped.