How would the route type affect the configuration if an OSPF configuration has several external routers?
If you have a primary exit with a secondary backup, you must choose E1, the primary with a lower default metric
than the secondary.
If you want to consider internal and external costs equally, use E2 routes.
If you want to leverage all paths to destinations, use E2 with the same default metric.
If you want to use the closest exit point, use E2 with appropriate seed metric.