A bridge fills the gap by joining to the teeth on either side. It is quicker and usually cheaper, and the cost is that two healthy teeth get prepared to carry it.
An implant replaces the root. Nothing is done to the neighbouring teeth, and because the post loads the bone the way a root does, the bone in that part of the jaw stays. Under a bridge it slowly does not.
Implants take months rather than weeks, cost more, and need enough bone to place into — which is what the 3D scan is for. If there is not enough, that is a conversation to have before you are committed, not during surgery.
Neither is automatically right. What should decide it is the state of the teeth either side of the gap, and how much bone you have.