Never say die is probably the best choice. It's useful for avoiding the low endurance penalty when the match wears on. The health boost is nice too but you can't bank on it. Grim determination is another strong choice for letting you fight on to the end, especially in close matches. Crowdpleaser works okay, but seems to be better when you're running defensive strategies - it will depend on how you run your glad. Iron jaw is too situational for my tastes and wars don't have access to strength of the crowd.