A lantern is 60gp weight, with 20gp per oil flask, while torches are 25gp weight each. For 1 hour of illumination, you'd need a lantern and 1 flasks of oil (80 gp weight) vs. 6 torches (150 gp weight). The longer you go, the more and more weight efficient lanterns are.
Shiroiken has said what I was aiming for.
I thought torches were good for 1 hour each. Or is that a 1e (as opposed to BX) thing?
A torch in both of those editions is good for an hour, and a flank of lantern oil for four hours.
AD&D: My DMG has a torch at 25cn weight (2.5lbs), a lantern at 60cn weight (6lbs), but a full flask at 20cn (2lbs). Not 80. So with the four hour duration we start at 8lbs total for the lantern and flask of oil vs 10lbs for four torches, and it gets better for the lantern from there, since another flask is only 2lbs and four more torches is another 10lbs.
For cost, a torch is a mere 1CP, 1/200th of a GP (people often forget that AD&D had 20sp to a gp and 5gp to a pp, instead of being completely powers of 10), where a hooded lantern is 7gp and a bullseye lantern 12gp, a flask of oil 1gp. So torches are always cheaper. But much more encumbering.
Torches actually cast wider light in AD&D, 40' radius compared to 30' for a lantern. A bullseye additionally can cast focused light 10' wide in one direction to 80'.
B/X: Uses a simplified encumbrance system. Weight for generic mundane equipment is abstracted to 80cn total and the DM can reserve judgement to declare someone heavily encumbered if a player abuses this. You only actually count weapons, armor, and treasure. So encumbrance doesn't really come into the comparison. Cost for Lantern 10gp, cost for flask of oil 2gp, cost for six torches 1gp, Torches remain more cost effective always. Both cast light in a 30' radius.
In both games lanterns may be shuttered to conceal the light without extinguishing it, they protect the flame from being extinguished by wind, and they can be set down conveniently without going out.
Also, flaming oil is a really handy weapon in both editions, so carrying flasks of oil is often a good idea either way.