Depends on what you are using them for in my opinion.
Stoneborn on Rakan can be really good cause he's a Censer user, meaning hitting your ult or W gives everyone who autos that person Ardent, or just hit your Q or E and apply it like you normally would. Before when Ardent had health drain on it, I used to play Stoneborn Karma, because that makes me apply Ardent with every ability. There was even a pro game where a Morgana ran Stoneborn for the same reason. The thing that people don't realize is that Ardent is applied on heal or shield. There is no condition on how much it healed, just a heal. So Rakan healing you for 1 hp from Stoneborn or Soraka healing you for 300 hp with her W/ult is the same Ardent effect. That was the trick I used to defeat the Star Guardian Invasion mode, just run Stoneborn on Soraka or Lux, build Ardent, and let every ability apply Ardent to your team.
Now, realize that because you don't have Courage, you don't have as much survivability as you did before. Hitting W or R gave you a shield, which you could use to eat some of the damage you'd take when you engaged before you use your E to dive out. You are squisher without it and can't stay in fights as long, so you can't hit W and stand there autoing someone once or twice before shielding your ADC. You have to be way more aware of what's happening around you to avoid damage cause you don't have that 300 extra health shield.
If your ADC is bad in lane, like a Vayne vs a Caitlyn, then Windspeakers might be better because every Q and shield in lane would be stronger and possibly help your ADC survive. If you're against hard engage like Thresh or Blitz, again Windspeakers might be enough to help your ADC survive the engage if they get caught, whereas Stoneborn/Courage doesn't help. Same vs like Syndra. Windspeakers might (unlikely) save them from a 7 ball Syndra ult whereas Stoneborn probably won't unless your ADC has tons of MR or insane amounts of attack speed/lifesteal.
I say go with what works for you. I mean, Fervor is the best keystone in terms of Damage for an attack speed ADC cause of the bonus stats you get, however, we all know that ADCs need to survive in order to do damage, so that's why some take Warlords cause the heal and burst of speed is sometimes all someone needs to survive an engage, or some take Stormraiders cause they can easily deal the damage but need the speed boost to actually finish a kill. Ideals only really work if everything works perfectly, which is far from what happens in general.
