Black and White: 400TMax. Long scale, sharp, fine grained. The most expandable b+w film made.
Originally Posted by Ed_Davor
C-41: Kodak Pro 100T. Incredible scale, low contrast, beautiful rich color balance without being overly saturated. (No longer made. Oh, how it broke my heart when they took this away.)
E-6: Kodak EPY. Same reasons as Pro 100T. For now, they still make it. (In 5x7 format, no less.)
Since your scenario hypothesizes that civilization is being destroyed, I guess if I can only grab one roll or box of film it would have to be the TMax because I would then be able to develop it. If humanity is being wiped out, there probably won't be any color labs still operating.