Let's look at this question from the perspective of the 4 Priorities:
1) Shelter: one can usually be put together faster if one has the appropriate cutting tools for saplings, vines, etc.
2) Water: requires a vessel to hold the water if it's going to be purified by a filter, chemicals, or boiling (fire). In the case of boiling, a firestarter of any type is a good thing to have.
3) Food: a knife can be used to cut vines & lines; striker on a flint or ferrocium rod; a spear point, skinning/prepping; cooking.
4) Fire or a source of heat: a knife can strike sparks; can be used to prep tender & wood; can make firemaking tools, a bow drill or a trough. A firestarter of any kind is good to have.
IMO: a good sturdy knife(ves) is actually more important than a firemaking kit(s ) but I carry multiples of each kind of steel tool and of fire making means (call me "insecure")
I'm a fan of a good knife, but I think I might disagree and rate fire as more important. Georgraphical differences, perhaps.
I always include fire in each of these categories, Wildman:
Shelter = warmth and protection from the elements and fire is a big part of that most of the year here. I can usually find deadwood and vines to build a shelter without using my knife.
Water = fire makes potable water for me by boiling to disinfect or to melt snow or ice.
Food = fire for cooking, even if we're taking a stove and not a campfire.
Fire = signalling, protection, light, comfort....