As a one-off even, definitely a migraine. I can handle a single migraine whereas being really tired when not being used to being tired is quite unpleasant.
With how it is like this where there are frequent migraines, definitely would rather have insomnia. A migraine once in a blue moon would be okay, but daily migraines would be insufferable. I've had recurring insomnia before, and though it sucks, it can be manageable.