Very well, thanks for the confirmation.
SmartApp Tokens are bound to a location context, i.e., you can only access items and installations that exist on the location where the SmartApp was installed, and one advantage of them is that you can integrate context-based APIs and features, such as Subscriptions and Schedules.
On the other hand, a Personal Access Token provides you access to your whole SmartThings ecosystem, which in my opinion is mostly useful for maintenance of your integrations e.g. to update the OAuth parameters of an ST Schema Integration or to patch the OAuth Scopes of a SmartApp Automation/Connector.
So, you may need to interact with both at some point, but for implementation purposes, I recommend you using SmartApp Tokens.