You're probably right. On 2018, Curry earned more than KD, and were around even in endorsements.Durant is definitely not more famous than Curry. The whole of Asia walks around with Curry jerseys after LeBron and even in Belgium (maybe Europe to an extent, I have no idea), Curry has a bigger reach and influence. He's the second name people know if they are not into basketball.
Curry has also topped the NBA Jersey Sales list in three consecutive seasons if I'm not mistaken. He is the face of their franchise, not Durant even though he might be the better player.
I think that the money players get from endorsements is quite a good indicative on how famous they are.
Career-wise though, it isn't even a question. Bar in that 2015-2016 season, KD was always mentioned as the rival to James.