The way I see it:
Lloris: A great goalkeeper and a good captain. Don't think it's idealer with armband gk, but it's ok when he has the right attitude and personality, like Lloris.
Dawson: Captain material, but unfortunately not good enough for the first eleven in a 4 man back line.
Kaboul: Captain material, maybe, but needs to improve his game, work on his concentration, before he can be the boss.
Vertonghen: Showed terrible attitude last year, which people will feel disqualifies him. I think he's the kind of player who will grow if he feels he's being respected. If he commits, signing a new contract, and gets to play his position as a CB, I think he will be more focused and dedicated wearing the armband, giving us a good captain and a better Vertonghen. Thus, I would go for this alternative.
Rose: Haha, No!
Walker: To me he always sees to try hard. With the captaincy he would try too hard. He would become a less good player given that responsibility.
Lennon: Like Walker, Lennon is best served not having to worry about others besides himself. Better alternative than Walker, but still not a natural leader in any way.
Sandro: The clown of the team, not the leader. Meget mature as a person and player given the responsibility, but needs to play on a more regular basis.
Capoue: When he started playing for us, he immediately looked a guy who can lead the troops. Needs to consolidate himself in the team and squad though, before he can takk the captaincy.
Bentaleb: Far to young and inexperienced still, but maybe a guy for the job in the future?
Dembele: If he were to become a more consistent performing DM, they maybe. Another one that I feel would grow with the job.
Lamela/Holtby/Chadli: In the Lennon category, without the 9 years of faithful service.
Eriksen: Could lead by example, but does not seem like a natural leader.
Soldado: Seems like a good guy and mature person. Would have to improve and establish himself as one of our star players before he could think about captaincy though.
Adebayor: Seems to like being respected and listened to. Might perform better given the honor of the captaincy. Might make him try too hard though, giving us tackles like the one he was sent off for, losing our game against Arse two years back.
Kane: Depends where his career takets him. Not sure if he'd be a good fin though.