If Lukaku goes and Valencia is not made permanent, i would take Dembele, with one between Lucasz Teodorczyk (Anderlecht) and Nicolai Jorgensen (Feyenoord). They are both 25 and are on a really good season.
I would take Youri Tielemans too, Everton are well stocked in the midfield, but im not sure about Barry and Besic... There are also rumors about a new try for Sigurdsson.
+ Keane.
I think Robles is doing good, so i dont think a new GK is really needed, or maybe one for the long term, like Pickford.