Twisted pair on XLR are the standard connector for AES3 balanced at 110 Ohm, BNC is the standard connector for AES3 unbalanced 75 Ohm and can be used for longer distances. RCA/Toslink are standard connectors for variant 2 known as SPDIF at 75 Ohm. AES3 balanced is used mostly in professional installations. To interchange XLR 110 Ohm balanced with unbalanced 75 Ohm you need an impedance converter. Mostly you'll see BNC to XLR converters. Which one sounds the best I have no idea I doubt I could tell in a controlled test. I use mogami XLR 110 Ohm cables.
Digital XLR vs Digital RCA
How would a digital XLR 110 ohm cable compare to a more costlier Silver 75 ohm RCA cable? I will do the comparison between the two myself and post my results but I thought I would ask for other people’s experience between these two types of cables.