Manual reset us the safest as it puts a person in control.
I would never use a cycling breaker that repeatedly closes into a short circuit fault condition, which can continue until the breaker fails, especially there is no one present to notice anything unusual going on.
Modified reset can be an issue when battery voltage sags and the heating resistor cannot cause enough heat to keep the breaker open, effectively causing the breaker to become a cycling breaker closing repeatedly into a short.
And I have seen cases of 12v
automotive type circuit breakers failing shorted with undesirable consequences. There is no 12V
automotive breaker made that is guaranteed to fail open and they only have a limited cycle life. Keeping cycle count down is good and best done with a manual reset.