For me it’s really about which resources can help speed up the victory paths.
Coffee is the overall winner for me because production is just that important - you’ll need buildings to support every victory condition, so better get them online fast.
Military path - Quinine, though it’s relatively scarce. It can add up to absurd levels if you get to the bottom of the Military attribute tree.
Scientific path - Tea, self-explanatory.
Cultural path - Kaolin, I guess? Maybe it’s my playstyle, but I’ve never suffered from lack of culture in my games, and you really only need it to get to Hegemony. Slotting Silk into your big cities has been sufficient enough, and Kaolin feels like an overkill in comparison. But sure, it won’t hurt.
Economic path only cares about quantity, so just slot accordingly. Anecdotally, Cocoa has been the most abundant factory resource in most of my games, so I slot it just to keep the points flowing.