I've only used SQLAlchemy, but I was seriously disappointed in its query builder interface. Building SQL queries seems like something that should be straightforward, but SQLAlchemy seems to throw Python magic at every thing, making the API very difficult to reason about. Worse, the documentation is very difficult to locate and navigate through. :(
I suspect this is particular to SQLAlchemy, but if not I'd prefer just to roll my own SQL going forward.
For example: my @movies = Schema->Movie->recent->starring("brad pitt")->all;, where recent is a method to restrict movies by age, and starring is a method to join on the actors table and restrict to a specific actor.