Think of CERN more as a cultural endeavor. It's the big, permanent, multigenerational physicists jamboree. The big colliders are not the goal, they are merely the foundation. The meat is in the detectors and experiments that are attached and that would not be possible elsewhere. Sure, the flagship experiments are also important in their own right, but their function as a rallying point, as a halo product for everything else that is happening there is a big reason why they should be funded.

A reactor project is a much less colorful affair, focused on a single deliverable. More contractors, less postgrads. There should be money for both.

ITER is just a demonstration system, it will hopefully produce a modest energy surplus. As just one step towards an actual useful fusion energy source, Its a proof of concept and it's cost need to be considered in the context of the whole endeavour.

The new collider will be a fully functional 'production' system that we fully expect to probe new physics, and test specific scenarios that will require it's particular capabilities. It's an end product and the latest in a highly successful, proven series of systems. By itself that doesn't make it worthwhile, but I think a high cost for a final system is a different beast from a high cost from a test project.

ITER's successor, DEMO is in planning, with a similar planned timeframe as this new collider... If we wanted to assign them to "generations", ITER should be compared against LHC.

ITER is considered very expensive exactly because nobody wants to spend all their money on one type of project, but in fact are concerned about ensuring their science funding is well rounded.