Its rather easy to vote Euwe the weakest world-champion.
But remember that before 1946 he held a full time job. The week after he won the world-championship he was back at his school as a math-teacher. Actually he has been world-champion twice. He also won the amateur-world-championship back somewhere in 192?.
In 1953 when he was no longer a young man he participated in the famous Zurich Tournament. In the first halve of this (30 round!) tournament he scored 7.5 /14 and won the brilliance-price twice. Replay his games against Geller and Najdorf and you will doubt if he really was so weak. More than that between 1930 and 1946 Botwinnik never won a single game against him.
Unfortunately the picture we have of him
is painted by Aljechins comments (who was not above
praising himself and demeaning his opponents) and by a rather repeated use in chess literature of his famous blunders and misadventures. His loss against Fischer for instance is widely quoted. But he played him 3 times and scored 1.5-1.5!.
In his book Fischer and his predecessors he mentions the five greatest world champions:
Lasker, Capablanca, Aljechin, Botwinnik and Fischer.
He claimed no place in chess history for himself.
I close with a quote from Bronstein:
"Euwe however is not easily flustered. Remember that in his lifetime he played more than seventy games with
Aljechin; the most feared attacking player of our time".