Benatia and Mangala aren't bad long-term options but at the exact moment, they are still a little raw and loose. Its a big jump from playing in Serie A and the Portuguese league to La Liga and Champions League and they'd both need at least a season or two to get truly comfortable. That leaves us with only Pique, Mascherano and maybe Bartra whom we can rely on to play composed.
While both are great prospects, we need someone who can immediately start more than ever which is why a big name will be the first CB. Luiz and Mangala would be my preference but only Luiz seems to be the only thing materializing in the media at the moment.
Also Flavia, you decided to focus on the fact that I thought Silva and Pique play identically. I wasn't saying Pique was on the same level as Thiago Silva, he isn't. While I wouldn't say he's miles ahead of Pique, I think a lot of it has to do with his maturity and age. He is more focused and disciplined than Pique but other than that, their overall approach to defending is very similar. That's what I was comparing, their approaches to defending, that contrast nicely with Luiz's approach.
I'm just hoping having Luiz next to him will force Pique to be more responsible and add some maturity to his game. In my opinion, that concentrated focus at all times is all that is lacking from Pique's game at the moment and that's something that can come with time. With Puyi gone now I am hopeful that Pique will begin to phase out the airheadedness and replace it with the attentiveness his mentor always tried to instill in him.