Filters are something that pains me a bit. Basically, while not insurmountable, I've main a reasonable investment and ultimately use a combination of B+W, Breakthrough, Lee, and Singh Ray filters and a cokin filter holder. But, people keep coming out with advancements that seem good, but just not yet good enough for me to swap out. Bit of the story of my photographic life at the moment.

I hadn't heard about the Hoya square system, but I have seen a lot of chatter about the Kase magnetic system. Here is a video by Nick Page comparing some recent filters (2020) and him selecting Kase. But, I've seen them around other places, generally getting a very good reception.

If I do anything with filters, as I seem to be staying with EF glass, I likely will pick up drop in filters for my RF-EF filter holder.