I wonder if you have any favorites among the Jarl candidates, regardless on which side you are. In my opinion there are good and bad apples on both sides; whichever side won the Civil War, there would still likely be both improvements and regress, depending on the hold.
Try to refrain from answering if you haven't seen all the Jarls on their thrones, or at least otherwise read through their dialogue as Jarls! You cannot know for sure if you haven't talked with all of them!
I hope to see good, civilized discussion and arguments for and against, and let's try not making this another Empire vs. Stormcloak topic. Let's keep the discussion on the Jarls' persona, please!
Haafingar isn't featured in the poll because it's Elisif the Fair either way. One could give their views on which Elisif they would prefer, though. I won't, at least not yet.
My picks:
Brina Merilis - well, more like any other Jarl in the game but Skald! He is a backward conservative, and some of his views are outright wrong and out of place. Brina seems like she is able to think rationally and could very well be able to improve the hold with her perseverance.
Dengeir of Stuhn - long political experience and has his heart in the right place. Unlike his predecessor (and successor...), he cares a lot about the hold's interests.
Thongvor Silver-Blood - this is a tough one. I don't... like Igmund that much. Don't know what it is exactly; it seems that Thongvor treats my character better than Igmund ever does! Besides, Igmund's playing into the pocket of the Thalmor. He should also pick his staff more closely. Thongvor, on the other hand, seems a smart, calculating, ruthless businessman who could be able to take care of the hold and reach some needed compromises to prevent tragedies. I'm not into mindlessly abusing aboriginals, though. Take Igmund's policy dealing with the Forsworn and everything else from Thongvor, and you'd have a decent Jarl (although with too much influence), I guess (or as decent as these two could ever be -- not that much).
Idgrod Ravencrone - while she might be a bit too odd (or just misunderstood?), she at least isn't a social climber like Sorli. I hate those who are only in it for themselves (~99%?). Idgrod also recognizes Falion isn't necessarily too bad. She should come forward more though and talk more to her people, trying to explain her views and visions. To care more about her people. I'd actually hope her daughter was the Jarl already. Idgrod Sr. could have a place as a compulsory court witch.
Laila Law-Giver - She's into stopping criminals in the city, and I'd rather not watch a mafia boss on an explicit throne. (Of course Maven still leads the town already, but it's good that there are more virtuous people in some power positions at least.)
Balgruuf the Greater - One of the wiser Jarls in the game, it seems. Cares about the hold, has his wits with him, has good tactical and political eye and can and will try to justify his own actions. A wise, charismatic leader.
Brunwulf Free-Winter - Don't know about this guy's leadership skills really, but at least he's one of the few in town who are not closed-minded brutes. This is a tough one, for Ulfric certainly has leadership skills, charisma and sense. He's a usurper though, and because of him there is yet another inner conflict. The conflict, whether for better or worse, is tearing the province apart while there are much bigger problems at hand (dragons).
Kraldar - actually hard to say. Much depends on the real reasons behind the Collapse of Winterhold (but because we know it's the timeline of the game development, let's assume the College had nothing to do with it and just had strong safeguard spells against it unlike the rest of the city). Kraldar might be a puppet for the College, but that might not be such a bad thing, either. Both Jarls here seem a bit indifferent about the normal folk, so let's go with the option who complains less and might have more in him to actually fix the town's sorry state. The fact that he, too, wants to keep Malur Seloth around could be a clue that he's corrupt, though.