It's not hard to find snippets, components or tools/toolkits in the open source world which holds the quality bar really high. Myself I use git, python, linux, gcc, bash and a whole range of others on a daily basis, and I love them.

But when it comes to bigger frameworks, which are intended for facilitating larger tasks of an application without much interference, I'm not as enthusiastic. I've tried a few commercial frameworks (game engines), which were okay, but all big open source frameworks which I've used myself, or which I have seen used in applications were decidedly worse than the commercial equivalent. But I'm not sure if my experience was typical.

Where have bigger open source frameworks for facilitating larger tasks of an application been able to equal or exceed commercial frameworks, and how were they better?