I own everything in print, as well as the PDF for the upcoming Journeys book. I use something from everything except Ruins of the North I think, but I’m gonna lean on that as soon as they go over the Misty Mountains.
Probably the least useful single product is the Lake-Town book that comes with the GM screen. Also I don’t actually hide behind a GM screen bit it does have all the charts and that’s helpful.
I also own three sets of the custom dice: two in bone, one in green. I hand out green bonus dice or fuck-you dice so they stand out.