I have them all, Shapton Pro 320, Shapton double thick 500, and Chosera 600.

In the 320 range, I’ve been using a mellow 325 DMT. Then either 600 Chosera or 500 Shapton HR, not a huge amount of difference in the performance of these two, they’re both good. The Shapton Glass 500 is cleaner, no blue mud like the 600C, and swarf is a lot easier to see on white vs dark blue. Get the double thick if you go that way, about 50% more $ for 2x as much stone.

I haven’t really compared the 320 Shapton Pro to the 325 DMT, but the stone is consistent while the diamond plate mellows with use over time.