Everyone has their own preference for various reasons so I guess there’s no better or worse. I am splitting between the two and will be using a Revelate Pika saddle bag in addition to the Wingnut Adventure backpack.
The backpack carries items I may need while riding such as food, day clothes, first aid kit, bike tools. The saddle bag is for stowage of night clothes, shell layer, bike spares, bathroom & chargers bag.
My primary driver is to get weight off my neck and back side due to long saddle hours.