I definitely preferred the sound mix in TLJ than in TFA. Not even a question. Visual effects too, but the one scene where Luke is fishing (where he jumps and grabs that huge stick over the water) looked pretty fake to me. And of course the cgi horses looked very bad to me too.
Lightsabers looked too much like they were actually there - reminded me of a lightsaber toy or replica in some shots. TFA’s sabers were definitely better for me. And the screen wipes were either out of place or too fast.
Overall I really loved how the movie looked and sounded though, a lot more than TFA.
Regarding lightsabers however, TFA > TLJ.
Again, waiting for the Blu-ray to see the full film, but the lightsabers in TFA looked like they had weight to them, as well as a feeling there was actual energy being emitted. Sure, the white core could have been brighter, but if they look more like the prequels then TFA that seems like a step too far in the opposite direction.
Speaking of SFX, from what I have seen in trailers I still think the ships look kinda fake, especially after seeing how beautiful Rogue One’s enhanced recreations of the ANH ships were. Maybe when building CGI ships it helps to actually have a real world reference (meaning, something actually fully built in the real world) before the model is created but, I know, too expensive.
I wouldn’t be surprised if the OT models were laser scanned for Rogue One.
As a matter of fact they DID! Well, with the Star Destroyers they acquired all of the model kits that were kitbashed to create the original Star Destroyer model, scanned them, and painstakingly recreated the original model in the computer. From there they added more details, usually from other parts of the same kits. This process was used for all the recreations of the original models, and they look more lifelike for it, whereas the ST’s Star Destroyers look alright, but they’re too flat in terms of surface detail and lack a physical presence that the R1 CGI ships had.
Here’s a video where John Knoll discusses his work on R1, and talks about the Star Destroyer in particular starting at 12:47: https://www.youtube.com/watch?v=JUafi3EWBY8