Next Generation Network (NGN) is envisage to integrate heterogeneous wireless systems. NGN is expected to have Quality as the major challenging issue. More specifically, NGN aims at providing guaranteed Quality of Service (QoS) and Quality of Experience (QoE) i.e. what quality a network provider can offer (or claims) & what quality user experiences. NGN user may be interested in changing its network operator or is forced to change the serving access point (AP) or base station (BS) in order to achieve a given level of QoE. Seamless transfer of user’s service from existing operator to a new operator bearing dissimilar radio access technology is called Vertical Handover (VHO). VHO decision may depend on the popular signal to noise ratio (SNR) criteria or other performance metrics like bit error rate, delay, jitter etc or combination of these metrics. Performance of candidate target network depends on the type of traffic i.e. whether conversational, streaming, interactive or background is implemented. Therefore to optimise VHO mechanism, all these metrics & traffic types should be evaluated. Paper elucidates contemporary VHO approaches i.e. hybrid ANP / RTOPSIS & Oliver blume method. Different Interworking scenarios & NGN testbeds are prepared considering Wi-Fi, WiMAX, UMTS etc. as the candidate networks. Neuro-fuzzy based MCDM weight assignment technique is applied & overall network cost function is computed based on Qualnet simulation. At the end of the paper investigation suggests that Blume algorithm is better than the hybrid ANP mechanism because it is simple to implement, more efficient (40 % more accurate), quickly computed (20 times less) and more dynamic (application oriented).