[Boulder]

My sources are just regular movies or TV series. I'll tune CRF as the last item once I've got all the rest in place.

--merange 44, basically lowering it from the default 57 which I understand is meant for 4K. For 720p, I've used 38 all the time. I think this is remains of littlepox's set of "tune film" parameters.
--splitrd-skip, in my old notes, I didn't find it cause any ill effects. Do you have any specific information why it's a "bad idea"?
--max-merge 2, values 3-4 tested and it caused blur. One of the things in x265 that is different from x264 - the slower presets don't mean similar quality at lower final bitrate
--deblock -2:-2, no need for intense deblocking according to my tests
--rdpenalty 1, trying to favour smaller blocks.
--qg-size 16, tested values from 64 to 8, 16 looked best (in terms of distortion in small details again) when compared frame-by-frame. Tested with a 720p encode, so I'll need to check that also with 1080p later.
--bframes 10, some video utilizes a lot of B-frames for some reason. Not a big slowdown so I've kept it at that all the time.