This is an interesting timeline worth exploring. Regardless of who ends up on the throne with Nicholas out of action, you could make a scenario for a better world or a much worse one, depending on your political views of what is better or worse and Russia's role in world affairs.
One of the things that weighs down any rational discussion of Nicholas II as a ruler is of course the tragic nature of his death. It's understandable, after all it's a bit hard to analyze, oh say, OJ Simpson's football career without at least acknowledging, ya know, the double murders. But that tragic death, and the political motivations of his killers and the results of the murder of him, and his entire family, made it quite hard for anyone to calmly discuss just how awful Nicholas was at being a tsar. And even those that condemn his inability to manage a modern state, or an ancient one for that matter, are often quick to point out that he was a nice guy and a wonderful family man, as if afraid to be accused of piling on. Nicholas II was a disaster. Not just because of his wife, or Rasputin, those both of those certainly didn't help. Nicholas II could do bad all by himself, and did it, a lot. He was that lethal combination of stubborn and indecisive you often find in deposed rulers, e.g., Charles I of England.
George, however better he might have been, was not exactly a win either. Oh sure everyone thought he was witty and lovely, but the job he would have been inheriting would not be to his natural strengths. You can be a witty King of England in 1890s, being a witty Tsar in the 1890s... The notion of absolute ruler of something the size and complexity of Russia in the 1890s is absolutely absurd. How can any man even pretend he had a clue of what went on in Russia if he was its ruler? Not even Bill Simmons at his worst could imagine his beloved fascist totem Bill Belichick pulling that job off. So poor witty George, the apple of his mother's eye, would look resplendent in a uniform, make deadpan remarks that would leave ambassadors in stitches, in more than three languages, and still come up empty. If you did not butterfly his TB, then he's dead before whatever is the equivalent of 1905 in TTL. And if he's alive... how much can he do? Granted, he'd be better suited to display at least an ounce of sanity more than Nicholas II did, and unless he too marries a loony German mystic he might be less inclined to rescind his promises to the kick the tires of constitutional monarchy, but he'd still have his rancid asshole uncles pushing him to restore the old ways and sooner or later WWI comes calling and then what...? Don't get me wrong, I'd still would enjoy reading the timeline and it'd be different. I just don't seeing it going all that diff for Russia, that's all.
Michael is intriguing. He had more sense than Nicholas, though that is not saying much. He was also willing to look reality in the face. But he spent his entire life running from his responsibility, in my view. I do not buy the notion of Michael the romantic falling in love with women and forsaking any chance at a throne out of a sheer stirring of loins and heart. He had many, many, many affairs and each time let the family bury them, and him. But the one time he married was when he found out Alexei had hemophilia. He literally quoted that as the reason he was marrying a commoner, to make sure he could do it before the family could force him to become the successor to Nicholas II again (he briefly was second in line between the death of George and birth of Alexei). Lets think about that for a moment. He realizes he's about to be made second in line, so he does the one thing that will guarantee he won't stay second in line by marrying a commoner. You can call it a fit of pique or love, but I think that's someone who doesn't want the job. Still, if George the lunger is on the throne, Michael might not have a chance to run away from power and he would dutifully allow himself to be placed upon the throne. Maybe a reluctant tsar would be a good thing for Russia. But would he have the strength of character to avoid the rancid asshole uncles giving him terrible advice? Would a man who is described as "naive" by more than one observer be good at the job? Would he grow into it? Once again, I am intrigued at a potential timeline. But it might all end in tears regardless. TTL may not have 1905 occur in 1905, but a 1905 will come and then what will Michael be able to do, realistically? And if TTL has a WWI, he might be much, much more effective than his other brothers at the top job, but still... I am not a Marxist, nor play one on TV, it's just hard to see a WWI that does not end with Russia in pieces due to it being held together by bullshit and bast shoes and fighting a war against modern states. That being said, I'd be the first in line to read any timeline anyone wants to write about it.