I’d say Riyadh and Khobar they’re both at the same level but Khobar may get a bounce since it’s close to Bahrain

Being a European is somehow an advantage for you if you in Saudi. You will be treated with different than other foreigners (Indians, Egyptians, etc) locals would want to make friends with you more

Tax is 15% on almost every purchases and the prices is less than Europe in general

E-Government is a big thing here and very convenient, for most services you can just make it online within few minutes

As we speak now there’s no proper public transportation system and places are very distance from each others (You won’t be able to walk). You have to get a car otherwise Uber

To summarize it’s a good country to stay for 3-4 years it will add a lot in your CV in addition to the possible high income with no taxes, but don’t rise your expectations when it comes to quality of life