If you’re looking for a 1:1 exact replica of what aired in theaters in 1977, the Silver Screen Edition is what you want.
If you’re looking for a 4K restoration to bring the actual picture quality more up to snuff with modern standards, 4K77 is what you want.
4K77 is also a “theatrical” experience. The Silver Screen Edition was restored from an HD scan of a LPP (IIRC it’s a dupe, but I can’t be sure), and the scan suffers from some light leak. While it was impressive and wonderful in 2016, I think it’s a much lower quality presentation than you’d probably get from an actual theatrical projection. 4K77 is simply better quality overall, so if someone is looking for a theatrical experience that isn’t reconstructed like Despecialized, I’d recommend 4K77 over the Silver Screen Edition.