Advice for the GSSR banner

Saber: What you have isn't the best, but then again, neither are any of the ones in the GSSR, unless you are desperate for an AOE saber. Personally I think you have other priorities.

Archer: You could go with this one since that's obviously what you lack. The risk here is that Arjuna isn't that good, so there's a 1/3 chance of disappointment.

Lancer: No need here imo. Lalter alone covers AOE with her NP and ST with her crits.

Rider: You are decently set for this one, though Anne and Mary lose some of their relevance later on when other riders outperform them, including almost everything on the rider banner. This is a good banner to roll, but not a high priority for you.

Caster: You have Waver, no need to roll this.

Assassin: 50/50 Jack or Jeanne. If you don't mind both then this is what I suggest.

Berserker: You have Herc and Fran so imo you have your anchor and farming needs sorted. No need to roll this one either.

I'd say go assassin/extra, since based on what you wrote you'd be happy with either option. Therefore, no disappointment.

Clicked save by accident, wasn't intended to make a comment but now I can't delete it so I'll toss in my opinion to fill the void:
For sabers, my personal favorite is Salter as she has the powerhouse AOE NP generally better than the SSRs available in this banner, for a price of an SR. I would hold of rolling in this group since in a couple of months Salter will be available on rate up that I'd recommend tossing some SQ/tickets at.