I'm going to assume we can offload certain players, and that players we want would come to us. Both of these things are sizeable assumptions and, in the real world, aren't hugely likely to occur.
I'd go out and buy a first choice left back, someone with real quality. Don't know much about this Alex Santos we're being linked with but I'd actually grab Alaba from Bayern (as my disclaimer at the start stated, I'm assuming we'd be able to get him, and he'd want to come, both of which are highly doubtful).
We need a top quality central/holding midfielder, a Makelele type with, perhaps, a bit more ability on the ball. Veratti of PSG would be ideal if you ask me. Busquets has been suggested but I'd worry whether he'd be able to cope with the physical demands of the Premier league, he does love a collapse and roll. There's a Swiss International called Granit Xhaka playing for Moenchengladbach who, I think, is still only 20 or 21 and looks fantastic, and might not cost the Earth. Lars Bender from Leverkusen is also worth a look, plus we'd have a player called Bender, which is almost worth signing him in it's own right. His brother Sven, at Dortmund, would be a good addition too. Ander Iturraspe from Bilbao is another good option, but Bilbao are notorious for squeezing every last penny out of buyers so wouldn't be cheap or easy. Nainggolan from Roma looks a good addition, but he's more "box to box" rather than strictly defensively minded, maybe a Pogba alternative if that deal goes south? Koke from Atletico would be ideal, but unlikely to happen.
I still think we need more pace and width, and I'd look to sell Navas and replace him with a far better version. Sterling has already been added, and I think he'll be a huge success at City. I'd look at adding someone else with pace and width also. Pedro is available, and not too expensive, he's better than Navas, scores more goals, and is more willing to go past the fullback. Marco Reus would be ideal, and you'd have to wonder, given Klopp has gone, and Dortmund seem to be dropping down the hierarchy in Germany, how difficult would it be to bring him to City? Over options are far less likely, people like Bale, and James Rodriguez, both would be extremely expensive and highly unlikely to consider a move to City.