I assume we are talking handguns only and we have long guns to cover other tasks. That said, my priority would be on self defense and survival.
1. Deep concealment: auto or revolver that can fit into pocket of dress slacks without excessive "printing".
2. High capacity, major caliber: most likely a semi-auto or revolver with a capacity greater than 7.
3. Large caliber, trail gun: most likely a large frame revolver or Glock 20
Ain't no way I am stopping at 3 though! I have to have a good BBQ gun (1911), a plinker/trainer (.22 rimfire) , a BFG (think real big), matched pair of S/A sixguns, military classics, a he thinks he's James Bond gun (Walther), a "wow that's weird" gun...