Need some Help with Gssr and team comp

Hello everyone so Ive been playing for a bit and have gotten pretty lucky I think. Now Im at the point where I need to set up farming team. the problem is I have no Idea what good team comp is. so here is my servants:

what would work the best? also final question, based on my current servants what do you think would be a good Gssr banner to go for? (in terms of filling game-play holes)

Please go here:

For farming like, straight up just raise Arash (-/-/6-10), Spartacus (-/10/9), Surfdred to max, and work on your Karna’s skills and levels.