It comes down to personal preference, and you’ve gotten some good advice already. Comfort in use is one of the primary considerations; some prefer:- backside Phillips over corkscrew, or no backside tools at all- no key ring attachment- 84, 91, or 93 mm- two or three layersIt’s also worth considering what tools you want. Main blade is sort of a given, but do you also want a small blade, saw, and or awl?