For our more junior roles, we leave it more open ended because candidates may not have a similar knowledge bases to the panel. For more senior roles we advise that if they pick technologies that are pertinent to the role and likely to be understood by senior/lead/staff engineers, the process will go better for candidates and panel members.

If I were in your position, one of understanding many complex systems, I would advise you to pick where you felt both strong and the panel was likely to have some entry point into.