For the money Laurentiis want for him, i will want someone more well-rounded, like Van Dijk. Koulibaly is average in aerial duel when i watched him up against Real Madrid 3 seasons ago. Further stats to back up my claim :
Here when compare to Cahill. who almost always managed over 3 aerial per game, Koulibaly aerial duel certainly a big weakness in his games. Serie A players can be overrated as well, you can look at Rugani for reference - this guy could have cost us 45m or more thanks to Sarri obsession with signing players used to work with him
And if you compare him to Van Dijk, Koulibaly look pathetically average for his 120m price tag, so no
Out of all those target you suggest, why dont include Niklas Sule as well, perhap if Bayern still want CHO badly enough, we can try a CHO + money deal. Conte wanted him 2 years ago and we already willing to paid more than what Bayern offered for him. That guy is build like a tank, tall, strong and still quite fast, already experienced at the highest level. I would say if we break the bank for a defender then i would pick him over these 5 you mentioned above