I am very happy to discuss this issue with you. As a Naruto fan, I personally think that the Sharingan of Uchiha Obito is not the strongest eye among Uchiha clan . The strongest Sharingan should be Uchiha Shisui 's kaleidoscope.
Let’s first talk about why Uchiha Madara is not considered a big boss, because Madara’s Sharingan eventually evolved into the Rinnegan, and even if Madara’s kaleidoscope fully opens Susanoo, I think it can be done with Shisui ’s ability, and his strength should not be much worse than Madara.

The great thing about Obito 's Sharingan is that it has its own time and space and can be transferred at will; that's why there were scenes in the early stage where he played with a group of ninjas in various virtual forms. Moreover, this ability is indeed a very powerful bug, which is almost difficult to break.
Generally speaking, except for genius ninjas like and the Fourth Hokage who can discover the weaknesses of the technique within one or two rounds, the rest of the ninjas can only be beaten.
Moreover, Obito at that time was still very young in terms of proficiency in using the Sharingan and combat experience. If Obito had encountered the Fourth Hokage in the later period, the Fourth Hokage might have been defeated.

Obito's Sharingan ability is indeed very strong, but a pair of Sharingan is required to be truly effective.
Obito is still very trustworthy in this regard. With his ability, it is easy to get the eyes back from Kakashi . Because this eye was a gift to celebrate Kakashi's promotion to Jonin, he has always maintained the single-eyed Sharingan.
The two Sharingan powers are one for defense and one for attack. Kakashi can always bring surprises to Obito, such as Deidara's broken arm, Deidara's fake self-explosion bomb, various kunai, nails, etc.

Having finished talking about Obito, let’s talk about Uchiha The strongest Sharingan—Uchiha Shisui!
Why do I think he is the strongest? Maybe it’s because I’ve heard too many rumors about him. They say that Shisui Shisui is the most powerful genjutsu among other gods.
We have never seen Shunshen Shisui. I think it should not be weaker than the yellow flash of the fourth generation. As for Betsutenjin, we have seen it. Uchiha Itachi also used Shisui's eyes to break free from the shackles of Filth Reincarnation .

We all know many things about Shisui from Itachi Uchiha’s mouth. It can be said that Shisui is Itachi’s life mentor. He not only played a good role in establishing the values of life, but also guided Itachi a lot in the attainments of ninjutsu.
From Naruto, we see Itachi's strength, and we can imagine how powerful Shisui is. When encountering the dual Sharingan Shisui, I dare say that in the early to mid-term, if Obito really fights Shisui, the outcome is still unknown.

Maybe many people will say that if Shisui is so powerful, will he lose an eye in a sneak attack? What I want to say is that people are sometimes negligent, let alone when they trust the higher-ups to launch a sneak attack.
There are many situations in Naruto where boats capsize in the ditch without any precautions. For masters, only one sneak attack is enough, because if you fail once, there will never be a second chance.
Danzo is an insidious person. Since he plans to attack Shisui, he will definitely not only take one eye, he will definitely want to get two eyes, and he will not let Shisui leave alive.

Under such circumstances, careful arrangements will definitely be made. There are many masters in the root organization. I don’t need to say more about this. Anyone who has watched Naruto knows it.
Under such circumstances, except for the loss of one eye in the initial sneak attack, Shisui later met Itachi. From the recall of the scene at that time, it can be seen that except for the loss of one eye, Shisui was unscathed.
He asserted that his eyes would bring disaster, so he left his last words and entrusted the eyes to Itachi.

So in my opinion, Shisui Sharingan is more powerful. If you have different opinions, please feel free to comment below!