Chronomancer attempted to merge with time and ended up dead.
T-Ray was a mystical Deadpool character with about zero ties to mutants and mutant classification.
Apocalypse hasn't ascended.
The Cuckoos have two dead sisters and haven't shown signs of transcendence.
X-Man is dead, so there's nothing conclusive.
Iceman is a confirmed omega. look at that...
Emma Frost can turn to diamond the same way colossus turns to steel. what's your point?
Jean Grey is another confirmed omega.
Marvel Girl is not confirmed, and likely IS NOT an omega simply because her mother is.
Shadow King was killed and took over a decade to pull himself together in the astral plane.
Deadpool isn't a mutant.
Cable has shown no signs of transcendence.
Stryfe is dead
Sinster has, also, shown NO SIGNS OF TRANSCENDENCE.
Quentin Quire is a third confirmed omega.
Holocaust at best underwent a secondary mutation. and now he's dead.
Onslaught wasn't a mutant.
Huntsman is a genetically manipulated weapon gone wrong. how does that at all factor in?
Fantomex made a machine out of his nervous system. GO WEAPON PLUS. how does that at all factor in?
Ultomiton (or whatever the hell Weapon XV was) also has no ties to mutants or mutation. have you been paying attention to this 'weapons' theory i've been presenting? ahem... how does that at all factor in?
Madeline Pryor is DEAD.
Typhoid won't ever transcend. deal with it.
you are not at all grasping the idea of transcendence. it's not just 'hey, they're not human anymore.' they EVOLVE into their potential past the boundaries of the human form. and, considering their potential is defined as "infinite," that specifically rules out all limited mutations, whether they're in human bodies or not.
madison jeffries was a mutant transmutator whose powers affected synthetic materials in the same way his brother's powers affected organics. he's always been limited to manipulating outside sources and has shown no ability to manipulate himself, unless you falsely include the idea that him merging with box is anything but a plot device... he's strong, yes. and now he's brainwashed and his entire character's been washed away by the weapon x project... don't expect a big "omega" revelation.
as for the scarlet witch, she certainly has incredible powers. but that doesn't specifically make her an omega. she's been described as the marvel of the lehnsherr bloodline, but that doesn't qualify her either. so, until she's either shown ascending to some higher form, or confirmed as an omega (who may or may not have already ascended,) we can't say.
as for the others that have transcended, there are big differences between BEING human still and imitating the human form. bobby's ice form is in the shape of his previous, flesh-and-blood body. but, he's easily able to leave that shape, and had shown the ability to alter his body's shape even before the "omega" classification was introduced. he could walk around as an ice dog, or a dragon, or a car, if he really wanted to. but a theme with bobby through the years is that he settles for a comfortable level beneath his potential, and that's an easy explanation as to why he hasn't been so inventive with his powers.
quentin quire went through a secondary mutation and became some variety of energy/gas. he reassumed a "human" form only in shape when he reappeared in endsong. he'd been stabbed through the shoulder by wolverine's claws and battered by archangel, and he just shrugged it off. the body itself was not flesh and blood, and only returned to a human shape because its a familiar form. whether quentin could be as creative as iceman when assuming a corporeal form, i have no idea. that's just the nature of the beast.
jean hasn't even been shown to ascend to her "transcendental level" yet, considering it was eluded that her ascension would allow her to replace the phoenix force in the cosmic hierarchy. so it's excusable that she's still very human-esque. and since we can't say either way what elixir's transcendence would look like, he's very much excused from speculation.
wanda was able to heal herself in a manner much akin to kid omega. but her powers are so very different than his, and considering the countless other things she's done without the "omega" label, it's not scientific to assume that because she healed her spine, she's suddenly omega. like i said, you can consider her to be schroedinger's cat for now. just wait for those quantum possibilities to collapse into one reality, whenever that may occur, and we'll have our answer.