Which setup is going to be more efficient with longer run times?

[Agro]

@el Capitan

I don’t think Buck Driver is an option because I only want single lithium cell input (or parallel) so ~3-4V.

There are buck drivers designed for 1s Li-ion input.

@jon_slider

A light with 3 leds is not more efficient than a light with 1 led, ime the opposite is true

the reason is that the 3 led light has a larger hotspot

so, efficiency favors a small hotspot (deep reflector)
efficiency favors Low CRI
Low CRI has more green, and less red output… green is a more efficient color for our vision

efficiency favors low lumen levels

sustained high lumen levels, require high battery capacity
sustained low lumens (less than 200), favors lower battery capacity

example, the sustained lumen capability of a single 18650 light is about 300 lumens constant

Good point, it’s about whether the OP want lm/W (total output) or cd/W (total intensity) or something between.
Fewer emitters (as well as smaller emitters) favour the latter, more favour the former.

Most earlier answers (mine included) offered exactly what the OP asked for - lm/W. But quite often this is not the right metric. Or rather - it’s not the only one that matters.

Also, as long as the throwiness gauge is on the right or in the middle or a little to the left, flat emitters are more efficient

So…a large flat die is the most efficient general-purpose option.