Audio quality is the same for all solutions, since it’s just tranport of digital data so… price, connectivity and ease-of-use matter.
Ethersound: 64 channels of 24-bit/48 kHz PCM audio, standard Ethernet cables and components.
+: standard network cable and components.
-: more expensive interfaces, due to the licensing.
MADI: The MADI format is capable of transmitting up to 64 audio channels (at standard sample rates of 44.1 or 48 kHz) on a standard 75 Ohms coaxial cable or an optical fibre cable. The 64-Channel mode was introduced officially in 2001. It allows for a maximum sample rate of 48 kHz + ca. 1%, corresponding to 32 channels at 24-bit / 96 kHz
+: less expensive interfaces.
-: coaxial cable (or optical) and not standard network cable and components…
OTHER (cheaper) solution: get the mini multi out card and use 3 times ADAT (so 24* 24-bit 48kHz)
If longer cablerun needed…
route the ADAT through this ADAT mulicore system: https://www.appsys.ch/
front: https://www.appsys.ch/images/stories/adx32a_adx64a/front_1600.jpg
dealer: https://www.musicstore.de/en_EN/CHF/Application-Systems-ADX-32A-/art-REC0007400-000
(only minus: this also uses a layer1 or less protocol so direct cablerun needed, not hubs or routers can be used… cfr. my recent topic)
+: very cheap, a quite standard cheap PCI ADAT card an be used in the recording computer. (https://www.rme-audio.de/en_products_hdsp_9652.php). Audio quality remains the same.
-: uh… direct cablerun needed, and the tiny ADAT optical cables of course 
Wouter