Each one of these is more resource intensive than the next. Bringing it down to Foocus which can run as low as 4gb VRAM.
IMHO Fluxx shows how dominate it is in the image generating scene. At the same time Juggernaut XL's newest update is nothing to shake a stick at... plus it runs at lower VRAM making it more accessible. If you want to get in the image generation game and you don't have a lot, FOOCUS is the way to go