So I came to Babylon 5 late in life, when my partner's mother revealed she had the entire box set on DVD. My partner had recently introduced me to The Expanse, which, like many, I consider the greatest sci fi TV show of all time - she described B5 to me thus: "Babylon 5 walked so the Expanse could run." Suffice to say, my expectations were sky high.
No other TV show has so greatly exceeded my expectations.
In B5 the only thing close to ineffable alien were the ones that went beyond the rim. Most of the day-to-day aliens were stand-ins for human nations and cultures.
The OPA and Mars were effectively the day-to-day aliens for the Expanse. The gate-builders were the ineffable aliens.
No other TV show has so greatly exceeded my expectations.