I HATE Zyuranger, I list it amongst the worst sentai shows with Ohranger and Hurricanger.
But, one thing I can say about Zyuranger that I can't about Oh or Hurricane is that Zyuranger was at least original. It was a completely different entry in the sentai series. A shitty one, but different nonetheless. Whereas its predecessors were rehashes -- Fiveman a Flashman-lite and Jetman owing its soul to Gatchaman -- Zyuranger was original.
But, man, I feel like I'm trapped in some bad LSD-stupor when I'm watching it. The cast is likable, despite half of them damn near infancy and Dragon Ranger is cool, but...those gnomes. Those disgraceful villains...the MUSIC! What the hell is that ED theme!?! That had my vote for worst sentai ED until Magiranger came along.
Zyuranger's main writer was Noboru Sugimura, who was also the main writer of Dai, Kaku and Oh. All of these shows have a certain quality that makes you feel like you're on a bad drug, but I think only Dai escaped unharmed, in the long run. Probably because the main villains weren't dumbasses.
The sentai supremacist in me doesn't want me to answer if its better than MMPR -- I don't really think a remake can be better than an original. I found MMPR to be equally hokey -- hokey wizardry and gnomes replaced by disgustingly P.C. and non-offensive happy antics, and acting straight out of porn. Both Zyu and MMPR are pretty much the television equivalent of being kicked in the balls.