Both would be good. Romagnoli plays left side, while Rugani is right. He'd be perfect as Chiellini's alternative. Even if we loan him out initially, he'd be a classy player to have in the pipeline. Him and Rugani in 3 years would be great.
- - - Updated - - -
I don't see the need for another striker. Tevez is world class and he will need to be replaced in a few years but Morata and Llorente are solid. If we're talking a prima punta, were not going to be able to upgrade much. Sure it would be nice to have lewandowski, but currently we have no attacking midfielders comfortable playing out wide. That's more of a pressing need. If you were to offer me hazard or lewandowski, it's hazard every time. Shaqiri fills the team need more than a striker, and further, he is a left shot, which is a commodity.