I have 200m agility xp. I hear a lot about these subjects.
S U O M I is the most likely, because he is fully prepared to spend the next 10 years nolifeing, and has an available living space for this time. He plays about 17 hours a day, and tries to be as perfect as possible all those hours. However, because of his refusal to merch, he has started some ridiculous "donating campaign" that means it will take him years longer than normal. (ex: he has to graahk to 200m rc, because he desperately needs money). He also is at risk of running out of cash before 200m mining, smith, magic currently.
Gertjaars no one takes seriously at maintaining rank 1. Just about everyone wants him to lose rank 1 to Zarfot. Gertjaars also has money troubles, as in the past he spent all his money just so that he could maintain rank 1. You'll see on his yt channel he's heavily leeching smokin mils by becoming their poster boy, saying to join them, as it has "pro members like gertjaars and telmomarques." He'll either run out of cash or lose out on efficiency to Zarfot when it comes to non-buyables.
Zarfot has 200m craft, herb, smith banked, and is so loaded that he will certainly become rank 1 if he keeps playing. He plays less to gain more than the top page overall, but since Zarfot spends time in something called real life, and is not a complete no lifer, there is a strong probability that he'll quit rs for real life before he ever gets 200m everything.
Lover Romeo has a 0% chance at 200m everything, sorry. Yes, he has 200m agility and 200m mining, but he is one of the most inefficient players there ever was. Atm, he's far more focused on 200m e hitting on girls than gaining xp.
Drumgun nolifes well, and has an available living space, but he only cares to train what he likes. For instance, he has 200m attack, defence, constitution, and mage, and is currently working on strength...probably getting 200m there too. However, he only has 15.7m slayer xp, which highlights his inefficiency for obvious reasons. He also does not merch, which adds to the number of hours needed, but he's still gotten a lot of money over the years (ex: all the combat drops, he once had a collection of thousands of whips). His bank probably still has or has had a large net amount, since he killed rock lobsters to 200m mage, which requires billions.
Those are some of the strongest candidates, and some of the names I've seen thrown around here. Regardless, don't expect 200m everything to happen for yeears.