Everyone has their own preference but there are times when one might be better than the other.
In older houses where the walls have damage that would require extensive and possibly costly repair, it is more advisable be to use wallpaper. Wallpaper can camouflage the damage nicely, as a wall covering. It's also better to use wallpaper for walls that are bowed or have ripple effects to the finish as it attracts the eye to the pattern and distracts from the flaws in the wall structure.
However, if your house is occupied with many small children with the high possibility of them damaging the walls (write or scratch on them), repairing wallpaper can be extensive! Given this case, you might opt to choose paint because painted walls would be easier to clean and/or fix when little hands have done their thing.
Paint is also better if you're the kind who likes to change things up often. Repainting a wall is cheaper and easier. Painting also offers the ability to coordinate the furnishings easier. (Neutral colors can still be rich and pleasing.)
Also consider the fact that paint can be applied anywhere. Semi gloss can go in a kitchen or a restroom while satin, eggshell and flat paints can go anywhere else. In contrast, wallpaper is not as that versatile. Applying wallpaper near areas of high steam or humidity is not recommended, so kitchens and bathrooms would not be a good idea. Wallpaper removal tools use high concentrations of steam to weaken the adhesive on the wallpaper that is why applications in those areas should be discouraged.
Another plus factor for paint is that painting walls can be done by anyone, even children. Just lay down floor protection and brush or roll away! Applying wallpaper is more complicated and probably not something you want the little ones to help with.
In conclusion, for me I would rather paint than cover the walls with wallpaper. I just feel like wallpaper is so ancient, but paint is so plain (?). Nevertheless, I'd give a very slight nod to the paint.