If you're going to wish for exotics that are more trouble than they are worth, why not wish for something stunning- I'm rather partial to the M1928 Thompson, myself. While I appreciate the reputation, and acknowledged that it was earned, the MP5 family just doesn't have the same type of class.

Or flamethrowers. Not the best survival weapon as they are kinda hard on game, but in a situtation where you need suppressive fire, why use lead? People are theoretically afraid of bullets but can't see them; people are terrified of the fire breathing dragon they just torqued off, and they can see the stream getting closer.

Although if we were wishing for survival guns, as I said a few weeks ago, a nice break action carbine, 16" barrels, double triggered, .22 over .30-30 or .308, with space for 8 .22s and 5 .30 calibers in the stock, and nice, big dot fibre optic sights with tritum inserts to keep them glowing no matter what.