[Tokumonkey]

My understanding is that the similarities between Power Rangers and Sentai is all over the map. I'm told there are a few Power Rangers series that barely deviate from the Super Sentai. I gather Samurai is like this, but I've only seen one episode; that episode was more or less exactly like the Sentai version, only with white people and awful acting. I gather the best Power Rangers series rewrite and recontextualize a great deal, using the Sentai as a springboard to make something new. RPM seems to be more or less the ultimate expression of that; the first half of the series uses some Go-Onger footage, but the vast majority is completely original. Engine Sentai Go-Onger and Power Rangers RPM are very different experiences that each stand on their own.

You may want to check out an episode or two of a couple of Sentai and compare them to their Power Rangers counterparts. The shows certainly *feel* different. The music in Sentai - opening and closing themes, but also audio cues - makes them feel really different. Sentai often spends time on roll calls, and the super-elaborate ones (Gekiranger, Shinkenger) may be my favorite flavor of cheese. The fight sequences often overlap, but not always, and transformation sequences differ. Power Rangers drops some Sentai content, but sometimes builds entirely new content in its place. (I'm very curious about all those extra Jungle Fury Rangers.)

People who've seen the entirety of each version of the shows can tell you more specifically which Sentai are must-watch and which you can skip because the Power Rangers version was better. If you track down Go-Busters, ToQger, Dairanger, or any series Jetman or before, you're getting something that largely (or wholly) doesn't exist in Power Rangers form.