Like an idiot I stained and finished our new wood window casing & sills
with Shellac several years ago. Now of course the sun & exposure has pretty
much taken their toll & I need to refinish.

I don't want a urethane since that yellows over time. I was thinking about
a pre-cat laquer or a water based polyurethane or varnish. Any preferences?
I'm leaning to the poly. It will be brushed on.