must agree that a big knife in urban survival will mostly take on weapon and crowbar duty. a can opener and crow bar would be more important tools. I have a small goose neck crow bar i use quite often, it's a good tool. vic pioneer would be my choice but if you lose enough fingers you may wish you had gone oht so i guess i'd have to go with that one and the dumpster mutt, just as it is. course i'd rather the oht was in alox. so.....

one implement: dumpster mutt
two: sak & crowbar/claw bar/molding bar
two knives: mutt & sak
scary giant sharp wrecking bar weapon: tough call...cgfbm or ganga ram. falcata's too much to carry.

of course i overlooked a good multitool. who the hell wants to hear that boring, obvious answer in an exciting survival thread?