Which workout timer mode should I choose?

Use HIIT or Tabata for scheduled work and recovery. Choose EMOM for a task that starts every minute, AMRAP for the most rounds within a fixed time, or For Time for a fixed task you want to finish against the clock.

A plan that says “repeat this circuit for eight minutes” fits AMRAP. A plan that says “complete three rounds within eight minutes” fits For Time. Look at whether your goal is a round count or a finish time.