A big part of the draw is the topicality: what kind of stuff is he interested in?
There's some pretty nifty stuff from Red Raven Games, like City of Iron and The Ancient World, that all has a very distinct almost-dreamlike soft palette of colors, thanks to Ryan's pretty distinct artwork.
If you've got enough players (and time!) then Warrior Knights from FFG is pretty fun, but you need at least 4 people and about 6 hours to really get your money's worth there.
Tiny Epic Galaxies has a great reputation, but I would avoid Tiny Epic Kingdoms, which had a good concept, but the combat model is broken.
If you want something a little more "groggy" but still with some wider appeal, check out either the original Quartermaster General game, or the original Dust boardgame (not the Dust Tactics minis game).
If you want more of a Gloomhaven-Style dungeon crawl, then the earlier suggestion of Descent is a good one, as would be Runebound, also from FFG. Runebound has a lot of expansions that increase the replayability, too.
If you want more of a 4x-like civ/city builder like Scythe, then look into 7 Wonders or Historia, or you could got the GMT route and look into Conquest of Paradise