I myself enjoy Hot springs story better than Game dev story partly because of the creativity you are allowed to impart. You can design your own hot springs and combine things together to make better combos. Game dev story limited the creative aspect except for the naming and game genre part.
i would say if you are a core video gamer in the past 20 years or so, you will be crazy for game dev story. but if you are looking forward to a casual game with SIMULATION feature and unique graphic, pick hotspring story. but i recommend them both, i just love them both!! HAHA