There is no "best gun" in pve because the concept of "best" is a bit more abstract as opposed to pvp where it is possible to a specific weapon due to the needs of the activity. Pve is more about personal expression. Unlike pvp, you have the luxury to move at you're own pace, doing things in an order and method you want to. That said, pve is also about longevity: how long you can survive when left to your own devices, dying has greater consequences and you can't just wait for a handy ammo crate to spawn at regular intervals. Therefore, I say there are certain themes of weapons you should look for: -weapons that have a high ammo capacity -weapons that have perks to recharge your abilities -weapons that that have perks that provide bonus buffs on kill -weapons that have fast reload speeds

Ill Will

Any decent scout rifle with Triple Tap + Firefly. Chaos Dogma/Genesis Chain are also top tier PvE weapons.