Who Should Be Captain If Riccardo Montolivo Leaves This Summer?

Montolivo is only the fourth Milan captain since 1982.  The three men that preceded him were giants in the history of the club—Franco Baresi (1982-1997), Paolo Maldini (1997-2009) and Massimo Ambrosini (2009-13).  The three men played a combined 62 seasons for the club and won 56 trophies—huge acts to follow Antonelli has been one of the team's leaders since arriving last January.

Montolivo has never shown the same kind of leadership, and that the team's decline came in his captaincy hasn't helped matters.  Now that the armband might be up for grabs, is there someone on the team that could be an improvement in the role?

There are a couple of contenders.  The obvious one is Ignazio Abate, who is the longest-tenured player on the team besides vice-captain Christian Abbiati.  
However, Abate has been injured on and off for years and doesn't see the field on a regular basis anymore.  Giving the armband to a player who may not play all that much seems like a lateral step at best for a team that has lacked real leadership from the position.

Two other players come to mind as major candidates: Giacomo Bonaventura and Luca Antonelli.
Bonaventura has only been with the team for two years, but they have both been productive.  He has easily been the best outfield player Milan has had since the beginning of last season.  He has scored 12 times, notched 11 assists and turned into the team's go-to set-piece taker.

More important than what he does with the ball has been his attitude.  When Filippo Inzaghi's team was at its lowest point last year and much of the team looked like they had simply given up, Bonaventura's head never dropped—exactly the kind of attitude the team needs right now.

Antonelli was the same way.  After arriving during the January transfer window, the left-back was a much-needed stabilizing force on Milan's back line.  He dovetailed well with Bonaventura when he ventured forward and helped to lock down his side of the defense.  
Of Milan chief executive Adriano Galliani's recent signings, Antonelli is clearly one of the best.

Who would make the better captain if Riccardo Montolivo leaves the team?

Luca Antonelli Giacomo Bonaventura

Both would be good choices for the armband.  Neither has been with the team for a long period of time, but Antonelli did come up through the team's youth system, giving him more of a foundation in the team's culture and lore.  That makes him the better choice between the two.

Frankly, either of them would be a massive upgrade over Montolivo, who simply hasn't shown any leadership ability since taking the armband after Ambrosini left.  
If Milan allows Montolivo to leave, giving the armband to a player like Antonelli will be a major lift.