Compressing my videos

H265, quality 21, MP3 192 Kbps audio and set the 'Optimise Video' setting to as low as you can bear. I found medium to be the best compromise.

For Youtube uploads in 4K, since h265 isn't currently supported, H264 @ quality 20, medium speed is pretty good and will be 1/4 the size of Sony's 4K-S option.

This is a bit of a fast-paced video, here's an index in case it helps:
0:58 - What is Youtube's quality like? (4K vs HD)
3:00 - h265 quality setting comparison and size
3:37 - 'Optimise video' feature: pros and cons
4:28 - Audio - Unfortunately the good FDK / HE settings have been removed from the latest version of Handbrake :(
5:46 - Which settings have I settled on for my video archives?