BH - Don't believe everything you're told by papers and SSN/BBC. I wouldn't rule us out of signing Aguero, although it is unlikely he may not want to join City and atm if Real sign Neymar and Adebayor then I don't see them signing him. I can see him signing for City, but I think there's a 10-15% chance he could join us.
As for Neymar. Yes, it doesn't look like he's coming, but at the time it didn't look like it...I was told otherwise however and also at the time Abramovich did have people negotiating with Neymar and I'm 90% sure he would have agreed to join us. For once though, Abramovich was being stubborn and wasn't prepared to offer an extra £5 million on a relatively unproven player, hopefully he made the right decision. It's not impossible that he will sign for Chelsea...I think it's more likely he will sign if he doesn't move this summer or in January. I think it's very unlikely he'll join this summer - 2-5% chance imo.
As for Pastore. He is a very talented player and there isn't much between him and Aguero. Aguero is more mature, but as Jamie says Pastore is still maturing and very quickly. With the players we have in our squad he will mature even more and develop in to just as good a player as Aguero. Also as Jamie says - he will fit into our team better and is more needed. Either would do wonders for us imo, but if you look at what they would bring to the team then Pastore is more needed because we need a playmaker and Pastore is one of the best there is and still developing.