Lets not discuss whether we (normal folks who simply drew SR and dont have frags/resources to 4* and buy frags books) will be even possible to obtain skillbooks or not.

In terms of current usefulness gnw super rares are superior to kage super rares. Ay is 1 round wonder designed to kill pretty much 1 key unit, while sasuke is just heavy nuke with a kit that resembles defense (even though he has pure nin immunity and super armor, hes actually squishy). Downside of sasuke is that he hits only 1 team without books.

I'm a big fan of sasuke and tried using him, i really did but kurama actually outperforms him in most of scenarios. Ay with current dodge/immune/no buffs meta has a hard time doing something and it's just 1 time thing for whole battle. Madara is good for konoha r2 burst that requires lots of chakra. While we can compare sasuke to naruto to some extent, we cant compare ay to madara because of 2 different roles in a team.

After necessary skillbooks Ay and Sasuke start to shine in 1v1 and 3v3 pvp respectively due to insane damage and scaling (1st with chakra, while 2nd with kills). Madara still retains his value as a chakra battery and kurama... hes just your generic move1 ninja that spams mysteries with immobile- in time his value will decrease as we get more and more overloaded kits that offer almost the same but are superior at something (guaranteed hit/additional effect), but he will get better once we get bond with edo minato.

Important thing is also looking at super rares. Hashirama is harder to obtain because you get free frags from 1 treasure unlike kage, where you get Itachi frags from 5. Hashirama is vastly superior to Itachi in 2v2 or 3v3 simply because of aoe undodgeable interrupt, strong cc, chakra drain and cross team heal for sages (all minatos, 2 of 5 mains) which always will be useful. Itachi on the other hand offers tankiness, 2x 2round chaos and strong standard. Chases are cool but nothing special. While in 1v1 it heavily depends on the team you use- both are really useful but hashirama simply offers more options.

So now that we know hashirama is better than itachi (in most cases), pulling gnw is for a long run better, since you get more useful super rare faster, ninja that retains his use (madara) and good frontline ninja with interruption (naruto+bond). And once you get hashirama, you c*e scrolls on kage, since you should be at least halfway to Itachi at this point.

Personally after GNW release i used about 1200 seals on kage to get sasuke and itachi and i consider it a big mistake. His skillbooks arent there yet, hes simply a dead ninja. Itachi is quite useful, but I'd much rather have hashirama and if I pulled from gnw back then, I'd have him. All what would be left is to use ~1000 seals to get sasuke and missing itachi frags. And now to have everything I need over 1500 seals given my current seal/hashi frag ratio. 500 seals make a difference.