Stannis Baratheon: As he first appears in A Clash of Kings Stannis is a terrible king. He was openly plotting to kill his brother, flaunting his illegitimacy, and without a doubt would have installed the Tyrells as the power behind the throne, whether he knew it or not. I think the show did too good a job of making him sympathetic. Then Renly just rules as he feels, no real strategy beyond the pageant. Look at Mace acting as Hand of the King! You give him an inch and he takes a mile. That would be his long term weakness in that the Tyrells might be a sweeter de-facto ruling house than Lannister, but they take root and would most likely have gummed up the court, leading to the resentment of lesser houses. This did look good, and would have probably served to smother his illegitimacy and kinslaying for a while, but it also heavily depended on the Tyrells for legitimacy. If is heirs prove incapable, what's stopping the next larger army from overthrowing the dynasty?ДЄside from that Renly did use a lot of pageantry. Renly doesn't really have a popular mandate outside the two initial houses which rose for him, and he has no legitimacy beyond the swords at his back, the other houses aren't likely to forget that. Renly's entire claim rests on having a big bally army to back it up, but once he's cowed his vassals, how does he manage when this feudal army disperses? My guess is rebellion after rebellion. But will Dorne? The Riverlands? The North? The Vale? Probably not. Now the stormlanders (for the most part) and The Reach might agree to this. He has the largest army therefore he gets to be king. His entire theory of his 'right' to kingship is that might makes right. Steven Atwell did a great essay on his theory of kingship, and having just gone through a reread of A Clash of Kings I can't help but agree that Renly would be a terrible king. Renly Baratheon: So, Renly is the most problematic of the kings I think. I think he would have grown into a excellent king. Then having marriageable brothers and sisters on hand (well, assuming Arya ever comes back) puts him in a good position to mediate in feudal politics with marriage alliances. But he was also able to largely keep recalcitrant bannermen in line and mediate disputes between them. Impulsive marriage decision aside, he made sound political choices to please his bannermen and create justice and showed some ability to administrate.

However, had he been able to keep his kingdom at peace, I think he would have made a good ruler. However, the Lannister/Tyrell victory at Blackwater made it difficult for him to really get things going, and after that he would probably have had to abandon the Riverlands in order to salvage the situation in the North, kinda dick move but a political reality for true. He probably would have been able to leverage a peace deal from his military situation if things had gone the other way, namely no ironborn invasion or Bolton treason. However, he was a brilliant battle commander and an excellent strategist and GRRM the gods did have to put their fingers on the scales to bring him down. He was only 15 when crowned, making him young and somewhat impulsive. Robb Stark: So Rob Stark is an interesting piece of the equation.

Jofferey: Sadistic little shit with no impulse control. To be clear some had potential to become good kings, others were pretty much doomed from the start. I'd really prefer to talk about the books rather than the show versions but, let's just say I don't think any of the claimants were actually great kings during the war, but especially in A Clash of Kings.

Battle of the 5 kings