Pellegrini in 13/14 played some of the best attacking football I've seen in the prem, up there with anything Ferguson or Wenger has produced. First half of that season they were sensational blowing teams away. Then, under huge pressure they held their nerve and won 5 on the spin to win the league. Playmakers like Silva Toure Nasri with overlapping full backs, they were a joy to watch. Even in that game at Anfield which his critics like to bring up, they wiped the floor with a very good Liverpool team for the majority of the game. Even as late as the start of this season City were beating the champions Chelsea with ease. It's perfectly understandable to see that injuries, focus on the champions league, key players losing form, and of course the announcement that he was going, derailed their league season. Ultimately he lost Silva De Bruyne and Toure for a whole chunk of the second half of the season. Where might they have finished if they had remained fit? I think he would be a fantastic manager for us, he would deliver a great brand of football, represent the club fantastically, be loyal (doubtful at his age he'd be using us as a stepping stone which Koeman or De Boer might for Barca) and deliver trophies as well as performing well in Europe.
I was in the Jose camp, but once that ship sailed I think Pellegrini is the stand out choice followed by Emery. Experience wise, stature in the game, brand of football, he is a level above De Boer and Koeman.