I tend to agree with Qwiss, but there's no magic universal formula. We need Aaron's drive forward, even if he's not super sharp (his effect vs spurs was visible, though he's still not in form). It also depends on his form on the day, and on opposition.
Looks to me like Ramsey and Xhaka behind Ozil is a good option, but a bit soft vs top teams (wouldn't play Utd like this, eg.). And when he's not playing well, Neny is a good sub (matches him for movement, though not for drive forward). And Xhaka's passes are needed (he's the best replacement for Santi in that respect, and better than Santi defensively, though sometimes his positioning is off). I also think Xhaka will improve with each game, and can be very valuable towards the latter part of the season.
This does leave Coq out, which is strange... but he's right back in there when more defensive stability is needed, and obviously as Santi's partner when he's back.