The most popular place to install a pull-up bar is the ceiling, followed by the wall and the hallway.
Here's Why
A ceiling-mounted pull-up bar offers the most room for pull-ups and other exercises. It makes your workouts on the bar super versatile. For example, a ceiling-mounted bar can also be used as an anchor for suspension trainers or power bands/resistance bands. You can also hang gymnastic rings from it, or even a swing for small kids.
The wall allows for a more discreet installation, for example, over a doorway. Technically, though, it only offers half the clearance of a ceiling-mounted bar. For this reason, you can't attach as many other pieces of fitness equipment to a wall-mounted bar. Usually, it's just suspension trainers or resistance bands. But for regular use, that's perfectly fine.
If you want to keep it super simple, you should go for a hallway pull-up bar. This is basically a wall-to-wall pull-up bar, also known as a corridor pull-up bar. These bars are very low-profile and can also be used as an anchor point for suspension trainers. The wall-to-wall pull-up bar also offers the safest pull-ups for the lowest price.
Insider tip: Desk jockeys will love the hallway pull-up bar, as it's especially great for hanging up shirts fresh from the dry cleaner!
The Bottom Line
If you want the most versatile pull-up bar, then this is your order of preference: Ceiling > Wall > Hallway.
If you want the most discreet pull-up bar with lots of grip variations, then this is your order of preference: Wall > Hallway > Ceiling.
If you want the simplest and cheapest pull-up bar, then you should follow this order of preference: Hallway > Wall or Ceiling.