sword/focus and?
PvE dungeons
In dungeons you should never range. If for any reason you do, use gs because at that point dps will be the least of your worries.
Situational. I like to use staff in dungeons sometimes. I don’t pick it for the damage, but for the moderate safety that Chaos Storm provides. Granted, it’s not perfect, but it’s the closest thing to a shield that I have. The extra retreat can also be handy.
Primarily, I use GS though, especially on my main Mesmer (as I have two). On my secondary Mesmer I will swap out staff for a GS depending on the fight: like the Jade Maw in fractals. I will use GS there because of the reflect bubbles on the colossi. It’s all person preference, though I would never use scepter except for fun.
PvE dungeons
In dungeons you should never range. If for any reason you do, use gs because at that point dps will be the least of your worries.
That’s so silly to say. You mine as well say you should never ever PUG or play with any new players ever then either.
S/F & S/S, even with PUGs. If the group is really, really bad, I’ll swap in GS.