One of the best things about those stories, especially the Final Fantasy series, is that the technology changes drastically from continent to continent and village to village. In most cases there is the evil empire or corporation that is technologically superior, but only because they cull it from everything and everyone around them.
The poverty stricken could be simple farmers or hunter/gatherer types who fear the technology that has oppressed them.
Another great thing is that magic can play a factor. Maybe the magic in your book is your electricity, or maybe it is a forgotten power which the hero holds the key to and the villain is seeking at all costs. Maybe the magic is far more powerful than any tech in the known world.
Books like that are popular right now because they identify with the struggle of modern life and the knowledge that there is a select 1% of humanity that is so rich and powerful that we may just be kept in the dark and controlled so that they can stay powerful.
Even still, your question is very broad and I'm not sure that any of this is applicable to your ideas and concept. Hopefully this helps with the technology question. Ultimately, I think a wide range of technology is best, it opens your book up to have more locations and differing landscapes in terms of a Manga or FF style storytelling.