im using the spigen liquid air case. i used a slightly bulkier and more protective ghostek for my Note 10+ for almost the whole year and i absolutely loved it. I ended up switching to the spigen for the sleek, thin feel and I've been really enjoying it, so i picked it up for my N20U also.

Im also planning on getting the AmFilm tempered glass protectors. supposedly they protect just as well as whitestone, with some alleging it's better. it's also slightly cheaper and comes with a second set of installation materials, including another protector.