I have no special insider knowledge. My impression, which I will gladly have corrected by those who know more, is that

• MIRI (formerly SIAI) was founded in Berkeley because that's where Eliezer was.
• Most of the rationalists in Berkeley are not MIRI employees.
• Most of the rationalists in Berkeley did not move to Berkeley because of MIRI or Eliezer or other rationalists.

But, again, this is vague impressions and guesswork and assumptions rather than actual knowledge. So let's assume for a moment that I'm entirely wrong and the Berkeley rationalist community is a consequence of MIRI. MIRI was founded about 16 years ago, and I think it's only in the last few years that the Berkeley rationalist community has been a big thing. That would suggest that the "build a rationalist community by starting an institution there" strategy takes 10 years or so to work.

If so, then good places to consider might be places that already have kinda-MIRI-like institutions. Perhaps Oxford (home of the Future of Humanity Institute, and also of Giving What We Can if you're the EA sort of rationalist) and to a lesser extent Cambridge (home of the Centre for the Study of Existential Risk). I think the FHI and the CSER are the nearest non-MIRI things to MIRI.