My thoughts on the subject?

Evan is arguably the most charismatic member of the team, as well as the one of the most physically powerful. When you take his gear into account he's also an incredibly well rounded combatant. He's already shown a 'team spirit' and consideration for the other Titans when he used his shield to block the shots and attacks of Lobo that were meant for another member of the team. However he is also seems immature and irresponsible, while his party boy outlook might not mesh very well with the coils of leadership.

Isaac, while bringing favourable comparisons to Superman, has been described several times as a 'rage monster'. Not a good trait in a leader, as one needs to be cool minded to make reasonable decisions. He can be our hammer or our anvil, but isn't equipped to ever lead. Not only that but he seems to have some issues with his unapproachable power levels already, feeling he stands alone from his teammates. Increase that by giving him command of the Titan's and that's just another level of separation. And, like Hillan noted, he charged off without the team, and it's not the first time he's done that. A leader needs to lead. They can't do that several blocks away.

Accelerate is apparently a great tactician. We haven't seen evidence of that yet in IC, but admitedly there's been very little chance to showcase his ability, so I'll let that slide. What has been shown is that he's as gun-ho as Isaac is, constantly leaving his allies in the dust. Difficult to avoid when your a speedster, but unlike Isaac he never even told the rest of the team he was leaving to combat the zombies on his own. A leader needs to communicate, and Rufus rarely does that. In fact until that last post he barely said a word to anyone else. 

Pistolera shares many of Accelerate's pros and cons, being possibly the most well trained member of the team, with a vicious tactical streak. She's also the closest thing that the team has to canonical Rose Wilson, and in unknown situations like this people like to cling to whatever shreds of familiarity they can find. Maybe the team would vote her in precisely because she's like Rose. However she's also very disparaging (Although at this early stage of the game they all seem pretty critical of their allies) of her team-mates, while quite obviously having secrets of her own. Personally I'd want Pistolera as leader for story-telling reasons, but I don't think the IC team would regard her that highly.

JC has an interesting power set while also displaying some concern for his fellow team mates when he approached Rose about her attitude towards Isaac. Unfortunately he never told anyone that's what he was doing, and then never told anyone Rose was leaving (Not Kindred's fault, of course, as she left then there was a time skip, but it's still going to count against JC.) He's had the least interaction with his team-mates, so for better or worse they're going to be disinclined to vote for him, merely because they don't know him as well.

Rhea, despite being the lest combat inclined, may actually be the best choice for an actual leader. She actually cares about her teammates, and has been one of the few to actively try and befriend the other Titan's. Obviously her lack of training and tactical acumen would be a hindrance, but she can always receive advice from Accelerate, Pistolera etc when the need arises.

As to the others, well I'm afraid I either haven't seen enough from them to judge yay or nay, or I just don't think the role would suit them at all. So in conclusion I would say either Rhea or Pistolera, and since I don't think I can vote for myself then I'm throwing my hat into Rhea's corner.