This is the real comment here. I've worked in all three, scrum, kanban and waterfall, and I know from personal experience that they all have their shortcomings and it really depends on what you are trying to deliver and how well your team responds. We've moved from waterfall to scrum to kanban and back and the one standout is clarity of minimum requirements and boy is that hard to get from the relevant people. If you don't get that then stick with waterfall because then no one is responsible!
Yeah, I didn't mention in my earlier comment but I've found that scrum does work better with larger teams because it adds ownership into the process. You can define ownership with Kanban (or any process) but it's not integrated into how it operates without some hacking.
edit I sometimes find myself in the position of apologist for Scrum, which is weird because I'm not that crazy about it, I'd almost always prefer to use something less heavyweight. But people are so quick to throw out the baby with the bathwater - there are a lot of great concepts in scrum, and it's quite interesting to see how all the parts interact when it's actually working.
