Here’s a list of countries that don’t have an extradition treaty with the US. Most of those countries are insufficiently white/rich to please Trump.
Russia doesn’t extradite, but has no Trump property, and I can’t imagine he’d feel terribly safe what with all the Novichok nerve agent floating around.
Dubai is another possibility. UAE doesn’t have an extradition treaty. It’s more Muslim than he’d probably prefer, but it’s a stable, wealthy international city. There is a Trump International Golf Club in Dubai. The Trump admin has done a lot of
grifting diplomacy with the Gulf states, so it seems like he’s prepared to maintain a long-term relationship with them.
So, if he does a run for the border, right now I’d see Dubai as a front-runner.