Portable GPS better than the car's built in one

Why (I think) owning a portable GPS device is often better than getting one built in to your next vehicle:

• You can find a model you like versus the model that comes with the vehicle.
• You can take it with you to navigate outside of the vehicle.
• They're often cheaper to update with new maps. In fact, many GPS companies offer a one-time fee for lifetime updates.
• The updates are usually available more often.
• You can transfer them to another vehicle, whether it's your next car or a rental.
• You're not stuck with it until you buy another vehicle.
• It can be placed in the most appropriate (and easily seen) location in the vehicle. You can even set it up so that the navigator (passenger) can see it.