If we're talking about who actually has a gap for Asllani to fill the answer is none of them do.
Arsenal: Janssen, Nobbs, Losada, Williamson, Bailey, van de Donk, Williams Corredera, Natalia, Carter, Yankey, Humphrey, Kelly, Smith, McCabe
Chelsea: Spence, Ji, Brett, Champan, Bright, Carney, Aluko, Kirby, Davison, Ayane, Farrow
City: Corboz, Christiansen, Scott, Walsh, Harding, Duggan, Ross, Parris(?)
City have the fewer midfielders and forwards and so by that logic they have more space for Asllani in the squad than the other two - but it isn't attack minded players which they could do with adding. They have the least amount of players in total because there aren't really any defensively minded ones for them to have to list where the other two do. But their number of options for the positions which Asllani could occupy is just as plentiful as what Arsenal and Chelsea have got.