I'm from Hungary, so I'd say ...
Péter Lékó
Reached World Championship match in 2004 (tied with Kramnik)
Peak rating over 2760
Judit Polgár
Greatest female chess player in history
Reached a peak rating of 2735 and ranked #8 in the world overall
Defeated multiple great world champions including Kasparov, Karpov, and Anand
For us here in the Philippines it is former world number 2 my idol Wesley So !!!
He will never be replaced as our GOAT with his sickening achievements.
How about your country?