Here are the shaders I use in bizhahk. I haven't update them in years because
a) some newer versions I tried in the past didn't work and
b) I'm quite happy with these as they are.
I use xbr, not xBRZ. They are quite similar, xBRZ is a fork of xbr.
I've created all these presets myself and in my system (AMD gpu) they work as they should. Whatever shader didn't work or I didn't want to use, I've deleted from the pack.
I've made extra presets with 6x scaling for you.
https://www.dropbox.com/s/zqi4svr5shzrlos/shaders%20for%20bizhawk.zip?dl=1
Unzip the shader zip file in Bizhawks' base folder. From the display configuration select the preset you want to use.
The most easy on the gpu is "Preset (2x) xbr-lv2.cgp".
I mostly use "Preset (4x) xbr-lv2_ + smart-blur_ + adaptive-sharpen.cgp".
The dither presets are for games with a lot of dithering.