Wallpaper on Plywood - 30 yrs old - paint or paper

I do not know what you are asking.
Is painted wall paper better that painted plywood?:huh:

I'd use a nice layer of BIN primer to seal the wallpaper from the paint, then paint over. You won't have any issues painting over the BIN with a latex

OK I'm a little confused also but here goes. You don't say what kind of room this is so I am going to assume it's a room that gets quite a bit of use.
As far as removing wall paper that has been up for 30 years the word nightmare comes to mind. Then to do anything with the plywood allthe paste (did you catch that Chris) has to be removed. Then the seams will have to be dealt with as in filled. And it's hard to paint plywood with out the grain showing thru.
As much as I don't like painted wallpaper it may be a better option. You don't say if the wallpaper is colored or has a pattern, if either I would prime with Cover Stain. It is oil based so be ready for the odor and the hassle of clean-up. But if you use a water based primer the water can loosen the paper. BIN would probably work but in this situation I would use the oil.
The 3rd option is remove all of it, update your insulation and wiring(if it needs it) and put up sheet rock.

Certainly cover stain as opposed to Bin, if , for some reason it cannot be removed.

Is this in a house? Never seen plywood walls in anything but a shed or barn.