In Wireless Sensor Networks (WSNs), energy efficiency used by sensor nodes is the most fundamental issue that requires special attention during the design of communication protocols. Every sensor node obtained its location information from GPS or other positioning system to send or receive data at any time. Energy wasted largely contributed by collision, idle listening, overhearing and over-emitting that occur at medium access control layer. One of the most widely used mechanism for energy saving in WSN, specifically at MAC layer is duty cycling. In addition to duty-cycle, network topology design also plays an important role in energy efficiency. In this paper, we discuss a simultaneous study on energy saving and QoS issues on WSN. Various protocols introduced nowadays to reduce energy usage. In these studies, we applied the enhanced adaptive duty cycle called Enhanced S-MAC (ESMAC) protocol and tested with several wireless network topologies such as mesh, grid and random topology in NS2. We determine quality of service (QoS) from three parameters that are Packet Delivery Ratio (PDR), Packet Loss, and Energy Consumption. The comparisons of QoS results has been made to determine the best wireless network topology. Simulation results show the mesh topology get the better results in average energy consumption, packet delivery ratio and packet loss. However, the random topology shows the best result in energy consumption for the number of packet generated. The success of this study will contribute in prolong network lifetime of WSN compare to SMAC