What is the preferred "Fixed Skill"

[Samseng Yik]

Usually i try to fix some lot cost skills that can be situational. But I feel I didn't well optimize enough.
But I would like to know what you all fixed for each heroes ?

[zimfier]

For Ironheart you can handle your AoE well enough if you have two healers and his Charge of Faith skill set as fixed. He needs a lot of damage and then he can one or two shot the encounters in the circus.