None of them are great, IMO, for the same reason that the Fallout TV show they're doing is almost certainly going to be trash (even if they kept all the woke nonsense out of it, which we know Amazon is pathologically incapable of doing) - at their core, the games are about individual player choice and experiences. Translating that to a TV screen just doesn't work because then it's Generic McGenericSon doing the main questline in the most generic way possible, losing 90% of the charm of the games (with one exception).

Going worst to best (and assuming the main 5 games):

Daggerfall is far and away the worst. Bethesda had to invent a space/time implosion to get a canon ending out of it, so trying to do it as a TV show would just end up souring people.

Skyrim is second worst - if it is just the Alduin arc it could maybe work, but if you pull the backdrop of the civil war and the Dominion out it the setting becomes a lot more of just generic fantasy. If the civil war and the Dominion are included, though, whichever way the story has the protagonist react to them is going to upset a lot of people (even though Ysgramor definitely had the only correct opinion on dealing with those pointy-ears). And parts of the main quest get weakened heavily without that backdrop (there's no need for the Graybeard peace conference, and Delphine and Esbern's caution becomes pointless. You might be able to make the embassy quest work but even that becomes rather silly without the political backdrop for providing a reason to not just slaughter the Thalmor to get the info)

Oblivion and Morrowind are roughly equal for me, as maybe doable but with big issues. For both, the main quest pulls out a lot easier than Skryim's does, but there's other problems.

For Oblivion, the biggest issue - and Bethesda did this some in Oblivion and ESO did it even more (at least in their trailers) - is that Hollywood will go hog-wild with Dagon = Satan which is not how it should be. Second is the issue that a lot of people have with the game - Oblivion Gates get real repetitive, real fast. If you limit it to just the Kvatch gate and the Great Gate it would solve that problem, but then your story about a daemonic invasion of the world will feature perilously few daemonic invaders. If you do include a bunch of gates (say, adding in the Allies for Bruma optional side mission where you close a gate for each major city), though, then the protagonist gets to do basically the same thing 8 times and by that point audiences will be yawning. Honestly, to adapt something from Oblivion, I think Knights of the Nine would work best (but, as with Skyrim, it risks becoming rather generic at that point)

For Morrowind, the main quest would work the best as stand-alone IMO but I just do not trust them to get the environment and the inherent ... alien-ness (is that a real word?) ... of it right. Plus, a lot of the charm (at least for me) is in books and drawn-out conversations and I don't think multiple episodes of "protagonist discusses metaphysics with Vivec" would go over well.

Which leads us to the last game, and the only one I think could work well - Arena. There's not much in the main quest that couldn't be adapted fairly easily, there's not much in the way of choice or branching paths, and pretty much all the side quests are randomly generated and pretty generic anyway so they could get added in pretty much anywhere if needed. And, on top of that, the main quest makes brief stops in each of the provinces but never spends much time or goes into too much depth in each of them. As a result, you could have 1-2 episode set-pieces in each province, show some cool stuff, and then leave to somewhere else and the next cool set piece, which seems to be the way Hollywood likes doing things.