Would like to grow indoor plans upside down, to save space...
Which are some good choice?
Would like those promoting more leaf growth?
Will the stem continues to grow at the same rate, as if it's planted straight?
Your goals of course will guide you. Most types of plants that you see growing from baskets could be grown upside down.
Rat-tail cactus, or Heart-leafed philodendron come to mind. I would avoid things that can support themselves, or they will just end up growing back up and taking up more space than if they were just in a hanging basket.