From my experience, the key feature for a pomodoro timer is that breaks should start automatically, whereas the next pomodoro should not. This way, even if you took a 6 minute break, you can have the full pomodoro. Plus, I prefer starting the focused work with a deliberate action (click).
Quite a lot of timers I tried, however, cannot do that. Great that this is possible here (settings)!
Why should either one start automatically? The one I'm using is manual in both cases, and that seems fine to me. Sometimes if I'm in the middle of something I go longer. That's good by me, as for me pomodoros are more about overcoming resistance to starting/continuing.
Quite a lot of timers I tried, however, cannot do that. Great that this is possible here (settings)!