I favor kanban processes - it locks in less at an organizational level and thus allows more freedom to make changes for the team. Though in my experience there is less change needed in the first place because the only processes specified are the ones that are locked in and everything else is whatever it takes to make it work.
Agile is rooted on focusing on people. Make a group of good people and empower them and they will create a process that works well. Also on the cases the process fail, they will change it. But if you go and decide the process, that's more than half the way towards a failure already.
Agile focusing on people is a good thing. People are number one, but agile has always acknowledged the roll of processes.
Ideally, even in a large organization, it should still be structured down into small teams that can self-manage. You'll end up with Conway's Law taking effect, but you'll also alleviate the O(n^2) communication problem. In my experience, it works a lot smoother than 50 person teams where everyone's tripping over each other all the time.
I never got on well with Scrum, especially with the way it has become synonymous with “agile”. Really a shame that “agile” which focused on people has been swamped as a term by Scrum which is process process process.