I mean, in a lot of ways this movie looks like a "World of the Coinless" movie, just in general tone and a few of the ideas. So, I could totally see this evolving from a pitch for a "Drakkon" or "Soul of the Dragon OGN" movie.
What is Power Rangers' "Beast Wars" or "Armada" or even "2007 movie", a reboot that over time has come to be as prominent and mentioned in the same breath as the first installment? Genuine question.
Oh, the fans definitely have their favorites. And a few have been fairly important to the brand. None of them are really "reboots", except one, but they basically start over from scratch most seasons and past shows usually don't have much impact on each other.
Just for the sake of argument:
The "Beast Wars": I'd go with In Space. It reignited interest in a brand that was on it's last legs, and showed that the show could have a more serious plot. And it basically kicked off a new golden age for the show. A fun show with memorable characters and villains and a really memorable ending.
The "Armada": In my mind, Armada was memorable for it's toy gimmicks and designs, so we have to go with a installment that had really memorable toys. And to me...that's the Ranger Keys from Super Megaforce. It's definitely not a good SHOW, but everyone loves those Ranger Keys. (Just...watch Gokaiger instead, if you have the option). If instead, we want to go with the "bringing the Japanese feel to American shores" aspect of Armada, then I'd go with Time Force. Time Force is a VERY faithful translation of the original Sentai version, keeping most of the plots. Time Force is also VERY good, being my personal favorite series (possibly because of nostalgia).
The "2007 Movie": It'd be REALLY easy to just say the 2017 Movie. It features "trouble teens" and re-imagines the original show for a new generation. And even the designs of the Zords feel like they were inspired by the Bay Transformers Movies. But, if we go with what the 2007 TF Movie WANTED to be, I think I have to mention RPM. RPM is the Ranger show with the most serious plot and is probably largely considered "the best one" by the fandom. It has a darker story and a few twists on the formula, like the "main character" NOT being the Red Ranger this time. And some of the jokes and characters still get referenced nowadays.
Dino Thunder, SPD, Jungle Fury, and Beast Morphers are all solid seasons, too. And Dino Charge's cast is really charming, even if the show itself is so-so to me personally.
But, the trinity of RPM, Time Force, and In Space are usually near the top of most people's lists.