At the end of the day, what really cost us was Kiwior, who is our budget defensive signing, who gave up a goal in Fulham's one and only attack. He cost us in an almost an identical manner to Salah's equaliser at the Emirates. The way we compress up the pitch and play in the opponents half, we allow 1-1 situations at the back and defenders who aren't top drawer will get exposed.
That's why we spend money on defenders and need to strengthen again given that Kiwior (as a CB), Tierney, Zinchenko, Calafiori, Tomiyasu are all unreliable or not good enough. The 3-2 base is the platform that allows the 5 in front to attack, hence why it's prioritised. That doesn't mean we shouldn't spend on the attack, we absolutely must, but the reason why one is highly prioritised is obvious.
We do need to strengthen the attack, and if I had to choose, I would probably go with a creative player. We aren't creating enough chances in open play.