Jigen is kind of hard to rank right now. I wanted to avoid ranking him until we see a little more of what Isshiki Otsutsuki can do. Nevertheless, he is clearly above Naruto and Sasuke. I could see him absorbing anything that juubi jinchuuriki Obito had to throw at him (truth seeking balls, bijuudamas, etc...). Unlike juubi jinchuuriki Obito, Jigen can also still casually use his space-time/interdimensional techniques (whereas Obito was nerfed from using kamui for some reason). The shrinking power might also be useful somehow.
For these reasons I would probably put Jigen above Rikudou Obito. Even so, I still don't know exactly how high I would put him since in terms of jutsu, I have yet to see him do anything that is particularly better than what Kaguya did.
Edit: There is one factor however that needs to be considered. Could Jigen actually resist infinite tsukuyomi? That is important when ranking him against Kaguya, Madara and Obito since all 3 of them could use it (even though Obito's took time since he had to use it through the shinju instead of awakening the rinne sharingan like Kaguya and Madara)
