Provided that he actually is available and attainable, my top pick would absolutely be Goncalo Ramos. On relatively modest wages and seemingly available for around 45m he's not only a "budget-friendly" option, but also the one that IMO offers most both in terms of attacking output as well as defensive contribution. Over the last 3 seasons, per/90, he has scored 0.66 non-penaly goals + and provided 0.12 assists. He also does the "dirty work" in terms of contributing defensively and has 1.25 tackles+interception per/90, and is also solid aerially with a 48%-win rate that would also benefit us defensively on set pieces. He also looses posession much less than any of the comparisons I've looked at.
Comparing Ramos with Ekitike, Sesko, David, Kolo Muani and Mateta, on metrics (all per/90) such as G-PK, Ast, npxG+xAG, npxG, xAG, np:G-xG, aerial won%, tkl+inter, pass compl% and possession lost, it's pretty clear that Ramos is the overall most complete striker out of them.
Assuming that our transfer budget is the reported 100m ish (Cunha deal + Mbuemo bid) + sales, I'd say that we would be mad to splash around 75m on any striker, and even that a player like Jonathan David on a "free" should be prioritized over Ekitike/Sesko if that enables us to strengthen further in the squad.