you want a farming build. nothing in the archer tree is better than that at SR3. now, scout is perfectly viable with SR3. you can speam spread shot when using retreat shot. marching fire for when retreat shot is off cooldown, and you have multishot, concentrated fire and assault shot for the bosses.
you will have a 15 target moving AOE attack + 3 extra targets attacked with spread shot and a 5 target moving AOE attack for when its off cooldown, which will increase your dungeon farming speed by a TON
the real reason why many SR3 go ranger 3 is for steady aim, a 10 second buff, and the duration perfectly matches the duration of retreat shot and steady aim
falconer is honestly underwhelming with a dungeon farmer, and falconer is better by going c3 for aiming. the build is too crowded with falconer in it, if you want to mix it in its better to just go full falconer instead or choose a class that actually benefits from falconer more such as cannoneer
you messed your character up by going archer3, its better to just go archer 3 - scout 2 - falconer 3 like braggi said and copy that korean guy on youtube