I should say first off that my personal pick out of those two would be Thavnair. As I said, the big weight-puller there between the two is actually the food: I have it in me to gain a taste for the kind of food we know Thavnair makes, while I would only grow to loathe something like Archon Loaf more and more as I ate it. There's a lot more factors in both nations' favor, but that's actually a pretty big one.
We learn a lot about Sharlayan from the Studium quests, and through that we see that they're not actually enormously conformist; they all broadly care about the pursuit of knowledge, sure, but there's a lot of breadth in that, a lot of care about different needs. They're not perfect, but there is very clearly a lot of willingness to let people find their thing and excel at it; hell, Thancred got a PhD in espionage, if a society gives someone that it's clearly one that's got an interest in nurturing all kinds of expertise.
There's also the fact that we do see that when problems actually hit Sharlayan, they can handle it pretty well. Amaurot's admittedly got a kinda broken sample pick here, because we've only really seen Amaurot when something's going cataclysmically wrong, but it really does seem even from off-handed comments in stories and text that Amaurotian life can just turn lethal at the drop of a goddamn hat (mostly thanks to that whole 'every single person has the power to create whatever their mind can imagine even if they don't want it to' thing). Combine that with the fact my overall feeling is that they're not good at all at registering or helping when someone's not well mentally (it's not just Hermes as evidence now, but also Lahabrea) and yeah, I don't think I'd feel very safe, comfortable or welcome in Amaurot. Sharlayan at least seems to get it, and there's a fairly low chance of someone suddenly summoning a nightmare-beast in the middle of the street.
And then there's the government. (Which I have too many thoughts on for 3k characters.)
I've previously felt like this is a bit of a bad faith argument on my part, because we're not really supposed to look at Amaurot as a real society with real societal problems and more just as a parable, so as mentioned the time I did flesh this out, throwing stones at their political status feels akin to criticizing Mayor Quimby for not being good for Springfield. But if I am treating it as a real society, which I'd have to if asking 'where in the game world would I want to live', I have to point out that everything we learned about the Convocation as a government is a problem for me on some level. It's essentially a council of unquestionable god-kings who only have to answer to themselves, can only be removed from office by their own decision to leave, and who select their own new members. That's a recipe for what I see as inevitable corruption; it's only a matter of time until someone's going to get into a seat with ill intentions, nobody's going to be able to remove them, and they're not going to leave until they've done whatever their secret goal was, at which point they've appointed who-knows-how-many similarly bad actors in their wake. When I started working through that overall approach in 6.0 it felt like a completely isolated just-for-fun hypothetical of 'what if this was real', but 6.2 Pandaemonium has actually shown that... uhm, yeah, corruption both can and has happened already, got REALLY BAD, and the only reason it stopped was because the culprit wasn't one of the god-kings while the one who found it was. (And hell, it didn't exactly end there or end well either...) Sharlayan may be a democracy with a conservative majority and disappointing decisions, but at least it's a democracy, I as a random-ass citizen would have some power to change it, which I would not in Amaurot (or most other nations in FFXIV, but this isn't about them).
Also I'm pretty sure I don't get to be hot for ten thousand years. Maybe this is just pessimism about my looks, but I'm pretty sure you just get what you get for your whole life, and that's not necessarily 'hot' just because we happen to be surrounded by pretty people. Add to that that I can't tell exactly what Amaurot would feel about wanting to change your own appearance, but that as a trans woman I'd kind of need whatever society I'm living in to be cool with that, and... yeah, I'm not taking 'everyone is hot' as a given, that might just be a result of the fact you have to try pretty hard to get the character creator to produce someone who isn't hot.
EDIT: Ugh, I wish we could remove tags on threads, because I noticed when writing this that someone out there decided to be boring and edgy. The worst combo.