Role or company?

Hi guys, long time listener, first time caller here. So my question boils down to this: what is better, a great position at a not-so-great company or a not-so-great position at a great company? I realize there's probably not a general answer to this so here are some more details in my case: - Both A and B are high profile names in their respective domain and have a strong online presence (Alexa top-500 global traffic rank); A serves mostly static content, B mostly dynamic. - Great position at company A: greenfield project, potentially high visibility, small agile team, significant autonomy to choose and build the whole stack. - Not-so-great company A: Primarily a media company, software is just a tool. High level decisions are taken by journalists and suits, often not the most internet and tech savvy individuals. Poor, unstable management (requirements changed drastically midway, we had to dump more than half of the code written up to that point...). With a few exceptions, the overall tech level is mediocre (e.g. ad-hoc version control). - Great company B: Built from the ground up as a software company; follows latest technologies and best practices. Challenging, stimulating environment. - Not-so-great position at company B: Ok that's a bit subjective but I mean something less "sexy" that a lead developer tackling huge scalability problems and playing with the latest toys. Think of non public facing roles, e.g. internal apps, tools support, automated testing, etc. For the sake of discussion, the question implies "all else being equal"; i.e. location, salary, perks, vacation days, double screen monitors, playroom and whatnot are assumed to be comparable or unimportant.