I suppose it all depends on what you’re willing to compromise.
Unless Mike Verta’s Legacy Edition is ever released and it’s everything he claims it to be, the 4KXX projects are the most pure restorations currently available with the highest resolution.
The versions without DNR have the least cosmetic work done but as a result, film grain is more prevalent.
There are some samples of 4K83 you can pull up on Youtube.
4K83 v1 (no DNR)
4K83 v.1 (DNR)
The no DNR is preferable to me, although the DNR version is more colorful. I’m not tech savvy to advise on why that is.
You can also find multiple samples of 4K77 without DNR on YouTube.
This fan trailer for 4K77 might be DNR but I’m not sure.
If you have a smart tv, I’d suggest pull open the samples on your screen to get an idea of how’d they’d look.
Fan projects such as Harmy’s Despecialized that aim to recreate the original versions will look better, but some of the edits may not flow as consistent with the main HD footage. Other projects sourced from the Blu Rays/ UHD discs will also inherit whatever methods were used by the studios to clean and sharpen the images.