Storing camera body with lens attached or just the body alone with body cap in dry cabinet? which is better?
Seriously ? I'm not aware of any recommendation regarding this.
However, if everytime you store your camera you have to remove the lens, put the cap (and vice-versa when retrieving the camera for usage) you will potentially introduce additional dust in the chamber.
And to start splitting hair diameterwise, you're wearing out the lens mounts a little each time, with the added risk of possibly putting metallic (or plastic) particles in the chamber.
Anyway, my camera "sleeps" in my backpack with its lens on.
If you keep it in the pack be sure to keep some desiccant packs in it to absorb the moisture it will collect when changing environments. If possible leave the back pack open to allow air circulation.
"However, if everytime you store your camera you have to remove the lens, then put it back on... you will introduce more dust in the chamber than without doing that." - Regarding that quote, wouldn't more dust will be introducted during lens removal compared to remaining static doing nothing about it; leaving the body with the lens?
@Michael Clark : no desiccant, but the bag does remain a little open, and if the camera took some rain, I let it dry outside of the bag.
Most photographers will store their cameras with a lens on - but they aren't looking at long term storage.
I would say that it doesn't matter - the actual environment as a whole is more important, however there is one caveat: Let us assume you have a weather sealed body with a weather sealed lens. This combination would be more humidity/dust resistant than a weather sealed body with a cap because there is no sealing on the cap for the camera mount. Whether this would be a practical or measurable difference is another question - it possibly isn't.
And as FredP points out correctly - there is a higher chance of dust or moisture getting inside when you change lenses/components, so the less you remove the lens (i.e. only when you need/want to try a different lens or for cleaning) the better.
Keep the lens attached. In every case I've seen the body cap provides a much looser seal than the a lens does. At best, you have a weather-sealed lens on a weather-sealed body which will prevent the vast majority of dust from entering either.
It is of course recommended to keep it in a dust-free environment at a reasonable temperature and humidity level. You will find the recommendations in your camera manual as Storage Conditions. In most cases though, we have little control over the environment. Sure, you can keep the camera in an air-tight container with some silica gel which you can replace every few months. Even if you have an air-conditioned home, humidity probably varies between days.