I think my son wins. He and I were watching that survival show on Discovery. After about 20 episodes, I asked him what his, one survival item would be if he was in that situation. He said, "a light saber". It's hard to argue with that.
It’s boring but safe and easy…Quality AR15 like BCM or a Colt LE Model with a sling, quality LPVO, and back up iron sights. In a situation like that ammo is your friend so whatever you can comfortably carry.
Even more boring a Glock 17 as a side arm.
If you want to just have a gun to get home and not make a lot of noise getting rid of an obstacle do a suppressed 10/22 with multiple 30 round mags.
Something in 5.56 for a rifle and 9mm in a pistol if i could only have 2. Id rather have a long range rifle in 308 as well. All common calibers you should be able to pick up.