I prefer Diomande from what I have seen - incredible on the ball but also has all the physical attributes you look for in a CB.
Appreciate it is in Liga Portugal, but Diomande has Van Dijk levels when it comes to Tackle % won and Aerial Duel % won. Inacio on the other hand is more progressive but has levels similar to Martinez in the above stats (in Liga Portugal).
Personally I would go for Diomande and see him as the Harry Maguire long-term replacement after his contract expires in 2026.