Neither for me.
We need to get the players that can help lay the groundwork for Emery’s plan. Possession and pressing. For me neither Martins or Shaqiri fit that bill. At least with Martins you might get unpredictability and width which is vital.
I would be looking at a striker/winger type. It is the biggest shortcut we can take to achieving something tangible next year. Get someone who can either play on the left or right, and help Lacazette and Aubameyang.
Probably impossible, but if we could land a Martial, Guedes, Werner (cost?), Rashford (would united consider it?), Pavón, it would give us a fighting chance.
I also like Brandt a lot, but i suspect like Werner, he would cost a bomb