The ranking they give is:
1. Ultima VII: The Black Gate
2. Ultima IV: Quest of the Avatar
3. Ultima V: Warriors of Destiny
4. Ultima VI: The False Prophet
5. Ultima VII Part Two: Serpent Isle
6. Ultima Underworld: The Stygian Abyss
7. Ultima III: Exodus
8. Ultima Underworld II: Labyrinth of Worlds
9. Ultima Online
10. Ultima I: The First Age of Darkness
and then 5 more, including Akalabeth.
I never played VII at all, but I did play II, III, and IV, and I agree with the relative rankings here.
Apparently a sequel to both was released in 2018 but was considered, charitably, "unfinished": https://en.wikipedia.org/wiki/Underworld_Ascendant -- What an ignominious ending to a well-loved series.
It's more than clear that old school gaming pioneers have completely ran out of ideas and are taking advantage of a nostalgic playerbase in order to keep the cash rolling in (I hear Garriott's latest NFT game has vanished), cratering their reputation in the process.
They are not the ones to push the medium further. Fresh ideas will require fresh, young, unknown visionaries.
Instead I got all the spoilers for Starflight from Usenet and finished it.