Oil- or water-based polyurethane to refinish stair banister?
I've been prejudiced toward oil based polys for years, but having used water based polys on some projects that weren't all the important, I've been impressed.   Water based is much less toxic, easier to clean up, more environmentally friendly and actually does a pretty good job. Seems to dry quicker and more solidly than oil based.  It also seems to sand easily between coats.  Being water based, it does tend to raise the grain on the first coat, but that's easily sanded down with fine sandpaper.  I won't be using oil based poly anymore.