For me it’s all about buffeting the weakest area. If I’m not getting 3-5 turn pop growth, then probably sage, otherwise, unless districts are already coming in quickly, then ebony.
Papyrus is certainly some cheap science, but it feels like a secondary goal for me early game. I tend to buy out makers quarters and units instead of trade early, because I’m just going to go upset potential trading partners by stealing their stuff. So I usually research EU and organized warfare using pops before buying my first luxuries, and then I’ll usually go to horses/copper/sage/ebony first, since my next tech for swords is pretty quick without extra help.