I'm looking for a compact platform to have in the car and sometimes home defense, already have a couple of rifles so just looking to add something more maneuverable and less expensive to practice with. What would be the best choice for durability and ease of maintenance?

All of this in the pistol configuration.

Those are all fine, but keep in mind that there's a reason 9mm sub guns are virtually gone him law enforcement armories in favor of 5.56 rifles and SBRs. The 9mm is not offering much ballistically for its size in those platforms. They're certainly capable of enhanced accuracy over a pistol, though.

There was just a thread duking it out between the GHM, MP5, and Scorpion that might provide some guidance, but all are good as well as the MPX (which several people suggested in that thread.

I think you should be looking at the Ruger PC carbine. If so, you have enough for an AR pistol as well! That way you can have your cake and eat it too.

If it's to be carried in a car, go with the least expensive since there's a good chance it will get stolen.

for a vehicle i wouldn't bother with any of the firearms you mentioned, for HD either of them would be sufficient but for a vehicle i think they would be to bulky and awkward. I'm comfortable with a full size pistol, a few extra magazines and a good holster for carrying while in a vehicle.

Other options:

If going 9mm CZ Scorpion pistol with folding brace (Tailhook Brace shown in pic):




If going 556, B&T APC556 or CZ Bren 805 pistol with brace:

B&T APC556:


Bren 805: