I'd suggest you plan for a Filter Holder system like LEE / Cokin / Tiffen. A number of companies (Schneider, Singh Ray, etc.) make excellent filters which can be used in the holders.
The biggest benefit of using a holder system is that every time you buy a lens of a different filter thread size, all you need is an adapter and the same filters can be used on all lenses.
5D3, 6D, 600D, RX100
16-35L, 24-70L II, 70-200L II, 100-400L, 50L, 85L II, 135L, 24TSE, 40, 100 macro, 18-55 II, 55-250 II, 600RT x 4
I come here to learn something new, not to learn how bad my gear is - I know that already ;-)!