Board Thread:Theories and Speculation/@comment-34277398-20180522015234/@comment-9782468-20180522024043

While the Sharingan is effective against Tailed Beasts, You have to be powerful enough to keep it under control. For example, Sasuke with 3 Tomoe Sharingan at the end of Part 1 would not be able to summon Kurama.

Obito is undoubtedly a powerful Uchiha, and he may very well be as strong as Madara was back before he died. It's been hinted that he was. However, I personally think Madara was stronger, if only by a small margin. Then that margin got very wide as soon as Madara got Hashi cells and Rinnegan in his prime and everything.