Yeah, honestly, the UK.
We've got some absolutely beautiful locations across the UK, lots of history, a fairly decent education system, free* University education, a great healthcare system at almost no cost (bar National Insurance), currently an economy that is doing relatively well, good defence (not that it plays on my mind), and I can respect and trust a lot of our institutions, such as the Police, the courts, even Parliament.
I think I prefer to live in England, but I've only lived in England and Wales out of the 4 countries. And Wales is nice and picturesque, but everything feels much more remote here. That is on account of my location within Wales, but even so. I'm in a relatively remote location in the UK, but it feels so much more active here.
There are other countries I think I could live in.
France, Germany, Italy, Greece. They're fairly similar to the UK, but I would miss the comforts of home.
I could live in the US too, but I think it would be a massive culture shock. It'd probably be one of the hardest places for me to live in the Western world.
(* There are tuition fees for universities, plus accommodation costs, but the Student Loans Company guarantees loans to students to cover them. The loans don't have to be paid back until you're earning over £17k a year. The amount you earn over £17k dictates what rate you pay back. Furthermore the interest rate is low, but I believe guaranteed to be at a fixed rate. If you don't pay it off within 25 years of being eligible to pay it back, it's written off)