About a month ago you said in another question that you had no offers. Perhaps that has changed. I hope so. But if not, I think your expectations are unrealistic. If you get an offer for a tenure track position from any of the top 20 institutions (in the US, say) or even the top 50, grab it. Carnegie Mellon is rated as 25 by USNews. Most academics would, I think, die to get an offer from CMU. Or University of Illinois--Urbana-Champaign, rated 49, I think.
But for general advice, treat a post-doc, not as a thing of value in itself, but as a bridge to a tenured position. It can be a solid bridge, but the goal is the tenure track position in which you can build a career.
If you have a choice to step directly into a permanent position at a good place (never mind top 20 or even top 120) take it and avoid the bridge.
The exception would be if you were offered a collaboration by a top researcher (no matter where) in your field whose own reputation would be a boost to you. The institution would matter very little. Joining the collaborative circle of a superstar, is a boost.
Another exception would be an offer of a post doc at a place that uses them to "take a close look" at potential permanent faculty. I don't know that many universities are even allowed to do that anymore, but it was possible in the past. And even in the past, universities of that calibre were still required to conduct an honest national (at least) search even when they had a favored candidate.
But I'd also suggest that, if you are having any difficulty in finding any position, then you broaden your search. Your question suggests you have too small a target. It is possible, of course that you are capable enough to get hired at a "top" institution, but in any given field, the total number of offerings by the top 20 in a give year probably isn't too far from 20 or so. And with hundreds of potential candidates for those few openings.