First one is the best. It's an old-school spy thriller rather than a traditional blockbuster actioner, the plot is intriguing from start to finish, Ethan has something approaching a character (until the train fight, he's much closer to a slightly nerdy analyst than a Bond figure) and De Palma's direction is absolutely superb: the sequence where Ethan recounts to Phelps what he thinks Phelps wants to hear while flashbacks show Ethan simultaneously working out what really happened is sensational storytelling. In principle I'm not fond of Phelps being the villain, even though I've only seen a few episodes of the original TV show, and the aforementioned train fight at the climax is a very sudden change in tone, but other than that it's a terrific film.
Second is Ghost Protocol, which is the ne plus ultra of the minimal-plot-maximum-stunts formula the M:I series now follows biblically. What stands it apart from the declining returns of the subsequent two films (I watched Fallout again when it was on TV a few days ago, and outside the bathroom fight it was as overextended and self-indulgent as the first time) is that it doesn't take itself seriously at all. It's a big cartoon with Ethan as Daffy Duck, the gadgets are wonderfully ludicrous and everything goes wrong in a delightfully silly way. The more self-important the series got under McQuarry, lionising Cruise as 'the manifestation of destiny' and so on, the more tiresome it became. Ghost Protocol isn't trying to show you how cool Tom Cruise is - precisely the opposite at times - it's trying to give you a bonkers good time, and at around 2hrs 15, doesn't overstay its welcome by too much (though does a bit).
Third I'd go for Rogue Nation even though it's a very mixed bag, but Rebecca Ferguson's Ilsa absolutely carries it, the opera scene is brilliant, and it's not excessively long. Downside is that, as mentioned, it marks the beginning of Hunt being lauded as The Greatest Man Who Ever Lived, it doesn't have Ghost Protocol's cheekiness, the villain is completely limp and the Syndicate doesn't really have any sort of plan and are treated as villainous simply for existing (the plot is told in a slightly labyrinthine way but there's not actually much there). It's a solid enough watch with some big highlights, but carries the smell of being a bit too proud of itself and its star.
II is next, because it's complete nonsense but hilariously entertaining and idiosyncratic in being so. The fact that nobody seems in on the joke of how cheesy everything is makes it all the funnier, and while I can't pretend that objectively it's not rather crap, in its weird and terrible way it might be one of the most enjoyable films of the series. I've also always found it very funny that the scientist at the beginning says he has twenty hours to fly from Sydney (very boring location, incidentally) to Atlanta, which I googled and means he's given himself a twenty-minute margin for error. And he seems to spend at least ten of those minutes watching children play ring-o-rosie in slow motion for some ungodly reason.
After that is III, which has a brilliant opening and villain from Philip Seymour Hoffman, but Abrams' direction gives it the candence of a (very expensive) TV movie, meaning it looks like it should be more impressive and exciting than it actually is. Cruise doesn't convince in his most challenging role to date (heterosexual human male) meaning the romance doesn't land; having the function of the macguffin literally be unknown kills any stakes; the reveal that the exciting opening was a fake-out is a bummer no matter how inevitable it was; everything to do with the agency mole, Hunt being framed, blah blah, is pure tedium. Despite Hoffman's best efforts, it feels very disposable.
Finally, yes, Fallout's my least favourite. It's horribly overlong, everything about the plot has been recycled ad nauseam throughout the series (made worse by
the original pitch sounding so fantastic: Hunt has to go undercover as an extremist and is forced to repeatedly compromise his morals to keep the mission on track), the stunts exist solely for their own sake and for bigging up Cruise, on top of even more of Rogue Nation's spiel about Hunt being the Spy Jesus. Ilsa and Julia are brought back with nothing of value to do, any trace of self-effacing humour has long been excised, the 'climax' goes on and on and on... the bathroom fight is great and Henry Cavill and Vanessa Kirby give very charismatic performances, but otherwise this is film driven purely by ego which quickly becomes exhausting. Oh, and Solomon Lane is still a flaccid villain who talks in meaningless NuTrek dramatic platitudes.