I don’t particularly hate or like any one database, but thinking about migrating the workloads that I have in mongo to Postgres just gives me no interest. Mongo solves the problems I have very well.
There's probably tons of small Mongo installations all over the internet doing great in their little niche. But the moment a project gets too big for Mongo, it becomes a problem very quickly. I suppose it's like comparing a bike to a car. If your problem is getting around a small town with nice weather, the bike wins. But the moment you need to move 5 people on the interstate to the next town in bad weather, there's no real choice besides the car.
That's been my experience with mongo every time