Hallucinated or not I found a better starting point on [3], a Reddit post of 2 years ago with a comment saying:
"Even professional mathematicians are barely qualified to choose the best mathematician in their narrow field of expertise, let alone in general…
(Before I left math, the most difficult work I encountered was by Michel Talagrand.)" [4] and last, but would be first indeed his own web page [5]. He even gives prizes ala Knuth for solving specific math problems.
Last, really few mentions in *stackexchange.com and Reddit.
[1] https://fr.wikipedia.org/wiki/Michel_Talagrand
[2] https://en.wikipedia.org/wiki/Michel_Talagrand
[3] https://chat.openai.com/share/39374448-da85-4897-977a-aaa37e...
[4] https://www.reddit.com/r/math/comments/s81ysm/who_would_you_...
[5] https://michel.talagrand.net/
[6] https://www.google.com/search?q=Michel+Talagrand+site%3Astac... and https://www.google.com/search?q=Michel+Talagrand+site%3Aredd...