Wireless Sensor Networks (WSNs) are essential for many modern monitoring systems, but their use is limited by the battery power of their sensor nodes. To make the network last as long as possible, the data routing algorithm must be efficient. The aim of this study is to show the differences and trade-offs between flat-based and hierarchical-based routing by focusing on three protocols: SPIN, LEACH and PEGASIS. Performance was measured through simulations using two metrics: network lifetime and energy consumption. The study's results show that while flat routing is simple to manage, the hierarchical methods are much better at saving energy and balancing the workload. However, choosing the optimal protocol for any application requires matching the protocol's characteristics to the application's priorities.