Well, get to technically eliminates me from the question because I wouldn’t want that kind of life at all.

However, it’s still a fun game to play, so I’m going to pretend I want it.

I want somewhere fairly mild in climate, but not totally without some variation. The question suggests that it shouldn’t be a current nation, and I think it’s a more enjoyable thing if I’m not taking over a country that’s not a monarchy.

So, I’m thinking Siam towards the end of its existence under that name. Since it’s me, not a copy of me that doesn’t know what I know, I could probably keep a similar balance between the surrounding interests as already happened, assuming that whatever method of transfer wouldn’t be negated by the fact that I’m a foreigner, and that the people would give me at least the same level of support at the beginning as existing kings had.

Ideally, I would get total support in the beginning and only have to worry about messing up, rather than just inheriting the usual mixed opinions about monarchies in general.

It’s always amazed me how Siam, and eventually Thailand, managed to keep as stable as they did on average. Somehow, even during early European colonization/imperialism, they kept afloat as their own nation.

So, if I’m gonna be king somewhere in the past, the combination of having at least a partial idea of how things happened and the benefits of the position there makes it the best choice I can think of.