When an eSIM is the better fit.
An eSIM is usually the simplest choice for a phone-centric trip. There is nothing extra to charge or carry, setup can happen before departure and you can keep your regular number available where the device supports dual SIM use.
Choose eSIM for one main traveller
It is a clean fit when your phone is the primary device and you only need occasional laptop tethering. Check that your phone is unlocked and supports eSIM before buying a plan.
Choose portable Wi-Fi for multiple devices
A hotspot can share one plan with phones, laptops and tablets. It adds another device to charge, but it can simplify connectivity for families or a small travelling team.
Compare the whole cost, not just the plan
Include device rental or purchase, battery life, data allowances, speed limits and roaming restrictions. The cheapest advertised plan is not always the least expensive usable setup.
Keep your backup simple
For important travel, keep a way to switch networks: an alternate eSIM, a local physical SIM where supported or a different carrier. A backup is most useful when it is already configured.
Make the decision in two questions.
How many devices need data, and how much extra equipment do you want to manage? One person with a modern phone will often prefer an eSIM. Several devices or travellers may benefit from a dedicated hotspot.