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 Babylon 5, you actually meet and converse with the aliens.
In the Expanse, you do not.