For urban survival, I'll take the Cybertool 34. It's big enough that it needs a sheath, but the best SAKs are all big enough that they need sheaths anyways. The screwdriver set on the Cybertool is VERY good. The shaft is long enough to reach many screws that you'd never get to with a normal multitool. You also get the very handy eyeglass screwdriver, which can be transferred to any SAK with a corkscrew.
There are many SAKs that are well suited for outdoor use. You just have to decide what features you want most, and leave out the features that aren't of top priority to you. For instance, I've never found scissors to be invaluable in outdoor scenarios, so I don't bother with them. I just use the knife blade for small jobs that I'd normally use scissors for. My favorite is the Tradesman. It has a big honking locking blade, the must-have saw, and a pretty good file. Some people may not find the file to be a priority, but I'll take it over a pair of scissors any day. Just wait until the first time comes, when your toenails have grown too long. Would you rather take down your nails with a file or a wimpy pair of tiny scissors? SAK scissors would never make it through my toenails. The file also has a plethora of uses, ranging from sharpening fishing hooks to fine detail woodwork. The file is also your only effective option on a SAK if you need to work with metal in any way. The file is a long-term survival must, but maybe not be a short-term outing kind of tool.
If youre just going out day hiking and stuff, you could really get away with a Rucksack, and never need another knife.
The metal handled SAKs are nice, but Ive developed an affinity to the nylon scales for outdoor use. The metal handled SAKS dont sport nifty features like toothpick, pen or tweezers. The nylon seems to be very durable, and does not get nearly as cold as the metal handled SAKS in the cooler months. The only downside to the nylon is that items like the toothpick dont stay in place as well as with the old cellidor handles. The locking blade SAKs only come with nylon handle scales, and the locking SAKs are much more ergonomic for extended use than any other SAK or multitool. The ergo-locking SAKs must be used to fully appreciate. The blades of the locking SAKs are large enough to actually perform as a redundant backup to a medium-sized fixed blade also. You wont do any chopping with a SAK blade, but itll handle quite a bit of work in a pinch, should something happen to your fixed blade. To tell you the truth, Id be perfectly comfortable in the north country, with just my Tradesman and a good hatchet.