Are we assuming that he has the Rinnegan in this match up? I wrote that under the impression that he only had MS, in which case yeah, he wouldn't be as strong as Madara or Itachi. Madara should be obvious as to why he would kill Obito low-mid difficulty. Itachi and Obito are probably even, strength wise, but theres no way at all Obito trumps Itachi's battle smarts. So Itachi defeats Obito by intelligence.
Nope.
Konan observed Obito extremely closely for the entire time she worked with him and had somehow figured out both possible flaw in Obitos flawless defence Kami Jutsu (that he is exposed when absorbing and can only exist in the diamention for 5 minutes at a time), engineered an exact situation in which she could kill him twice, first by blowing up dog tags when he attempted to relocate her (which though he avoided it did considerable damage to him), and again when she opened up a cassium full of explosive tags so that they would blow up continuously for over 5 minutes and he only walked away because he had a spare sharigan to sacrifice.
Obito didn't seem the kind of guy who would give up an eye so it was fairly obivous that for whatever reason, he just simply couldn't teleport while he was untouchable. He had to come out, in order to suck himself back in the vortex. He could do that against Charka eating bugs because they pocessed no immediate risk, or being burnt, but he couldn't take explosions idly.
She had all the information she needed, and engineered two very good plans for killing him and she still failed. No amount of inteligence can kill him if you lack the means. And believe me, she was the only person up to that point, aside from the 4th to stick much damage on him, along with the poison guy. Itachi cannot beat Obito alone in any state, most characters in the manga cannot hurt Obito so it hardly a discredit to him but he doesn't have the same option to try and sucide.
Moving on, I really don't think having both of his eyes changes the situation that much because already he's pretty much unkillable. Bee, Guy, Kakashi and Naruto fought him at the same time and they still didn't defeat him. There is only 2 things that change with him having his eyes.
Most importently, no body can hurt him. Most of the counteracts made at Obito has involved Kakashi's eye. So it pretty much removed the only kink in his defence that they could force against him.
Secondly, since he's already invinciable, adding the power to kill people remotely is merely overkill for him. It merely makes him more godly then he already is.
Obito is one of the most powerful, living character in the manga just based on the fact that he is nearly impossible to kill. He doesn't need to wreak entire contients with his pressence, but the fact he can outright ignore any attack until he feels ready to do something.