LvG, Rinus Michels and Kovacs are the clear top 3. Erik ten Hag over Koeman and de Boer for sure, and in terms as for Ajax maybe just Erik Ten Hag on par with Cruyff.
Cruyff never won the league with Ajax, did win the cup twice and won the Europacup II which might give him the edge.
Erik ten Hag finished 1st, four times in four full seasons, with a few cup victories and beautiful football, made Ajax competitive in Europe again. It is all context based though, as Ajax was really crap in the years before Ten Hag, especially in Europe.
However, I don't know exactly how strong PSV was in their time before Cruyff.
Jack Reynolds is also there, too long ago to form a meaningful opinion on my side. Someone more knowledgeable might give more context.
But I'm pretty sure most Ajax fans would have EtH ahead of de Boer and Koeman.