I think you will find a number of threads here about country selections and stereotypes. Stereotypes have some value, but you have to be conscious that they are just stereotypes. APs are all so individual, it can be hard to discern what is their personality and what is their culture, attributable to the country of origin.
I also had a Thai au pair, and it's funny because friends who also had a Thai au pair previously told me how great the household help was because "it's their culture." You can guess where this is going. My Thai au pair was one of the messiest I've hosted. I liked her well enough--she was sweet and meant well-- but I had wished those friends had not made that comment to me because she definitely did not then meet my expectation. And I am mainly just talking about her cleaning up after herself. She liked to cook Thai food for herself during the day (great!), and she'd usually do her dishes but leave the stove a grease-splattered mess. She's drop her coat wherever, leave her wallet on the sofa, lose car keys. . . She was ok with my kids. They are older.
I have hosted APs from 7 different countries and various parts of the world. I remain open to any country (I think

) and it comes down to other factors for me. Like strong English skills is one of my top factors, for example.
And on the flip side of this, we had only one really horrible match in our years of hosting, and AP from Italy. And it has been interesting how that experience, which left me a little traumatized, has now colored my views of Italy and Italians. Not really rational, but it just reminds me of this horrible experience. . .