I like my KSC75, but i can’t really compare to the SR850 as i have not heard that one. What i can say though, is that the KSC75 ear mount is a bit of an acquired taste. I was Ok with it, but i ordered a headband from parts express (look in this thread : 🔶 Koss KSC-75 / X ) to use them as an ordinary headphone. Was quite cheap and for me the comfort was instantly better.
Also, i did change the pads for Yaxi ones for better comfort and a bit better midrange and bass, but with both mods i fear the budget might be breached 