One factor that _might_ influence your choice of C vs. CF lenses is the filter size.
The C-series lenses standardized on the B50 (Bay-50 or bayonet 50) attachment, which as one might suspect is a 50mm bayonet.
The later CF (and subsequent) lenses standardized on a B60 60mm bayonet.
If you use filters you can standardize on B60 for the CF lenses, and use them on the earlier C lenses with a B50/B60 adapter (the lens hoods won't fit), or
you can get all B50 filters and use them only on the C-series lenses.
There are a couple of lenses in each series that use larger filter sizes, notably the short FL wide-angle ones.