I'm really indifferent - Higuain, Aubameyang, Ibrahimovic, Benzema. All would move the scoring needle. The next layer of Lukaku, Morata, etc., would also improve us drastically. That's at least 6 players that Wenger should be able to make a bid for.
Someone not mentioned who is worth an audacious bid is Robert Lewandowski. Pep will not take him to replace Aguero. Maybe he would like a new challenge, and that probably leaves only Madrid as a viable alternative, particularly if United do not make the Champions League. However, a Lewandowski move to Madrid would likely free up Benzema. In the end, it's up to Wenger to end up without a striker.