This is my take on it:

Roland would be great at making snap decisions and wouldn't buckle under fear or pressure. The negative of this of course is most his plans wouldn't be too thought out and his more straight forward approach to things might get them into more trouble.

Lumen seems like he would be the opposite. His plans would be well thought out and he might even have a more creative approach to problems. But his reluctance and doubt in himself might keep him back from making fast calls and could lead to others doubting him as well.

Circe seems to know her shit and is confident about that. She wouldn't have a problem giving an order in any situation, but her distrust of others along with not being the most personable could lead to in team conflict or disobedience from the rest.

Ceiran I think is close to Lumen in the 'thinks things out' camp, but his lack of control with the twitch demon could really cause some problems if it took over at the wrong time.

In the end, it's gonna be a heck of a ride for whoever gets the title.