[Vuejs]-Vuetify open dialog with custom logic

You don’t really need to use v-slot:activator="{on}" in the first example – <v-dialog> tags can be activated without that (as described in the “Without activator” example here).

However, the recommended way for me personally would be the second example you have provided – the one that uses v-on to trigger the dialog, as it handles opening the dialog without writing an extra function to set one of your data variables.