Although there may be really slight differences of behaviour in specific applications e.g. capacitor switching or motor starting (better done by a contactor up to 12kV though !!), SF6 and vacuum are equivalent in terms of performance, reliability and cost for general purpose.
Beware of...
Live tank CB's are generally cheaper, however overall project cost usually ends up similar since you have to add on cost of separate CT's, CT structure, foundations, floor space, connections & connectors, labour,...
Dead tank CB's enable you to consider the CB as a complete subsystem from the...
