Enquiring about postdoc opportunities: should I contact professor directly or via recommendation/networking?
I think that the professor contacting their colleague about how wonderful you are is far superior to you cold emailing. The recipient doesn't know you and you have no reputation with them, so it is easy to just ignore any email unless they are actively seeking people.
It is especially effective if the two professors know one another already. This is one reason that I recommend every young scholar to spend some effort on expanding their circle of contacts and collaborators.
A colleague won't be ignored, but you might be.