Routing protocols are the basic process mechanisms needed to route the packets from one node to another node in Mobile Ad Hoc Networks when nodes are not within the transmission range. The performance of these routing protocols is affected by various factors in particular node density, mobility model, transmission range, etc.. In this paper, simulation studies are conducted to analyse the performance of two proactive (DSDV and OLSR) and two reactive (DSR and AODV) routing protocols using different traffic classes. The performance of these routing protocols are analysed by using QoS performance metrics like packet delivery ratio, throughput, end-to-end delay, normalized routing overhead and jitter. The afore mentioned metrics are evaluated by varying node density, transmission rate and transmission range. Affect of node density, transmission rate and transmission range on various metrics is demonstrated through well defined graphs. Experimental results illustrates that AODV is the best on majority set of performance metrics especially in the context of multimedia jitter.