Different OS platforms offer advantages and disadvantages in term of security as far as user is concerned. Some maybe open-source, others may not be. Some may have huge user base, others may have a moderate user base. Some maybe more and others maybe less leaky than others. Some maybe more tamper resistant and some less tamper resistance than others. Some maybe more resistant to malware and other maybe less resistant to malware and so on. What is the preferred OS platform with respect to TBB in the sense of minimization of security risks?