DAM - the amount of damage a weapon does
DPS - amount of damage per shot a weapon does


Which one is the better to look at when chosing a weapon?

DPS is not the amount of damage per shot, it's damage per second.

That being said, I usually go for DPS for automatic weapons and DAM for snipers.

All you gotta remember, according to the tip on the load screen, use a weapon with high DAM for penetrating armour, and high DPS for non armoured targets.

Gun with high DPS is best used against unarmored targets, while high damage is better for punching trough armor. So, SMG against geckos and Anti-Materiel Rifle against Deathclaws.

AP ammo makes low damage weapons more effective against armor, but it's even better to use AP ammo with a high damage weapon

Which one is more important will depend on what you're fighting. Soft enemies like Cazadors have no appreciable armor but lots of hitpoints, and raw damage per second is what you need to kill them efficiently. For enemies that have armor, their Damage Threshold is subtracted from every hit you deliver. The 9mm submachinegun is a high-dps weapon that only offers 11 damage per each bullet, so fighting an opponent with a DT of 11 will basically do nothing but annoy them with this weapon.

Short story: neither one is more important than the other. They are equally important in different situations.

To explain why high DPS is for unarmored and DAM is for armored, basically the targets DT, or damage threshold, is subtracted from each shot so if you're fighting say a deathclaw which has 15 dt and your weapon is for instance 20 dam and 100 dps you are effectively doing 5 damage per shot and therefore only 25 damage every second (200/20 is 5 shots per second) whereas if you had a weapon that did 50 DAM and 50 DPS it would do 35 damage per second to said deathclaw. However AP ammo kinda throws a wrench into this, most AP ammo subtracts 15 DT from the target and makes the shot do 5% less damage so if you had AP for your low DAM high DPS weapon it would be considerably better again.