The credential is the part of an access control system people actually touch, so it is the part they have opinions about. The opinions are usually right about the convenience and wrong about the security.
Fobs and cards
Cheap to issue, easy to revoke the moment somebody leaves, and nobody needs training. That combination is why they remain the default.
The weakness is that they are shareable. A fob tells you which credential opened a door. It does not tell you which person was holding it. For most doors that distinction never matters. For a few it matters a great deal, and those are the doors worth thinking about separately.
Keypads
No hardware to issue, no hardware to lose, and no cost per additional user. That makes them a good fit for doors used by rotating contractors, deliveries, or anyone you would rather not hand a fob to.
The trade is that codes get shared and then never changed. A keypad code has a way of becoming common knowledge slowly enough that nobody notices it happening. If a door is on a keypad, the code needs an owner and a schedule.
Mobile credentials
Harder to pass around, because handing over your phone is a much bigger ask than handing over a fob. Issued and revoked remotely, which is genuinely useful across multiple sites.
They are a poor fit where phones are locked away, where hands are full, or where the workforce would rather not install a company app on a personal device. That last one is a people problem rather than a technical one, and it is the one that most often derails a rollout.
Why most buildings run a mix
Because the doors are not all the same. Fobs for staff on the main entrance, a keypad on the service door, mobile on the handful of doors where you need to know which person rather than which credential. That is a design decision made while walking the building, not a product chosen at the counter.
The question that sorts it
For each door, ask what you would want the log to tell you if something happened behind it. If the honest answer is that a credential number would be enough, a fob is enough. If you would want a person, the credential has to be harder to hand over.
What happens when somebody leaves
This is the scenario that separates a working system from a list of doors, and it is worth walking through before choosing anything.
With a fob or card, the credential is revoked centrally and the physical fob stops working whether or not it comes back. That is the main practical advantage over a key, and it is a large one.
With a shared keypad code, nothing happens until somebody changes the code, and then everybody who legitimately used it has to be told the new one. That friction is exactly why codes do not get changed, so a keypad door needs either individual codes or a genuine schedule.
With a mobile credential, access is withdrawn remotely and immediately, which is the strongest position of the three and the reason multi-site operators tend toward them.
The system is only as good as the process, though. All three depend on somebody being told that the person has left, on the day. That is an HR question rather than a hardware one, and it is where most access control quietly fails.
Which doors justify which credential is something Elite Security works out on the walk-through rather than assuming. More like this in the blog, and access control is where to start.