Manhattan can divide himself into as many projections of himself as he likes and, presumably, still exert as much power from each of those "clones" as he does when he is just one.
He can effectively just think where he wants to be and he's there making him far faster than superman.
Doomsday's been in a film? Was that an animated one?
Dr. Manhattan is a living being, right?
I think "sentient" would be more accurate.
He's described as "ageless and indestructable"
At the end of "Watchmen" he is to leave the known universe and go and create life. Effectively stating that he's away to be a God. Do any of the people on that list have anything remotely resembling that kind of power?
It's all very well being able to exert massive amounts of kinetic force like Superman or Doomsday but I don't think that's of any use against a being that doesn't feel physical pain anyway.
I'm guessing he would just disassemble all of them.
A few of the geniuses on the list might be able to replicate what Manhattan did to himself though...Then we'd really have a fight.