One of the greatest sources of those Lem's "predictions" is his Summa Technologiae, which was recently translated into English - https://www.amazon.com/s?search-alias=stripbooks&field-isbn=...

It's from the 60s and contains strikingly good predictions on AI, SETI, Virtual Realities, nanotechnology, multiple universes, the future of our civilization etc.etc.

Also, if you're a fan of R.Kurzweil and others predicting the technological singularity - reading Golem XIV (from 80s.) - https://en.wikipedia.org/wiki/Golem_XIV - is a must.

His earliest works weren't quite on par with the later. He said just as much himself.

This is true of pretty much every author.

Sure, just that "all his works are worth reading" isn't quite true. 'The Man from Mars' or 'The Astronauts' are fairly cringe-worthy. Not that it has stopped me from reading..

What would your top Lem book recommendation be?

Cyberiad is really fun.

Mine would be “the futurologist convention” (or however it was translated to English) - it is rather short, but I found it an extremely fun read, with just enough text and story to support the idea and no fluff. YMMV.

All "serious" stories in Tichy series are worth checking out. The humorous ones are good too, just unsure how much is going to be lost in English translation.