I´d definetly say stick. If you can get ceylon especially. I brewed a winter porter with those. Broke crumbled them by hand into some vodka where I let them sit for a few days, then dumped it all into secondary and let it sit more. Breaking those suckers open released a wave of aroma that was almost unreal. Any stick should be far better than powder as there the oils and goodness are already gone, but those ceylons just left everything in the dust. Pure beauty.
IIRC I used two sticks in an imperial porter with a lot of other additions, so one or two for you I´d say. Maybe start with one, taste, and go from there. Just try to get good ceylons.