I have used all three pretty extensively.
Tris:
Most interchangable, easiest to clean, rock solid connection that can stand up to heavy mechanical loads. These are the best for systems that do not need to make a lot of connect-disconnect actions or where you need mechanical strength. They are also very nice because they can be adapted so many ways, add sensors, gauges etc. without any work.
Cams, polysulphone or brass
A little cheaper than tris and definitely easy for changing connections. I really like these a lot and will use them in the future as well. I will still use tris though in certain spots around my rig for rigid connections, sensor placement, etc.
QD's
Don't make any sense to me. Not stainless, more expensive than cams, restricted flow, few connectivity options. I would not purchase these.