Comic creators love to portray godlike characters in their stories. It adds something to them; it allows creators and readers both to get into the minds of beings that are by their very nature unknowable and inject something human into them, to meld the sacred and profane. One of the most popular examples of this is Watchmen's Doctor Manhattan- a man who basically becomes a science god but still has a glimmer of humanity in him.
Another example of this is Lucifer Morningstar. The biblical Devil, he was introduced in The Sandman before abandoning Hell, going to Earth, and getting his own book about his adventures. If Doctor Manhattan were to clash with Lucifer Morningstar, who would win?
11 Doctor Manhattan: Recreator Of Worlds
The New 52 was an ambitious move by DC to garner new readers by wiping much of their slate clean, much like Crisis On Infinite Earths was before it. However, it never gained the success of its fabled predecessor and was shuttered about five years after its inception. There were a lot of changes to the universe that were great, and some that weren't, but DC came up with a novel reason for all of these changes.
Doctor Manhattan came to the DC Universe and decided to start messing around with it. He went back in time, stopping certain events and literally stole time from the universe, basically recreating the DC Universe.
10 Lucifer Morningstar: First Fallen
Lucifer was once God's favorite archangel and he was also the first rebel. Cast out of Heaven, he became the ruler of Hell. It's all pretty standard to people who are familiar with Judeo-Christian tradition. Lucifer was the first being to question God and led the war against Heaven for uncountable years after that until he got tired of it.
Lucifer has been conscious since the beginning of the all things and has watched creation develop. He has seen and done things that no other being has, giving him more experience in just about everything than most beings can possibly imagine.
9 Doctor Manhattan: Master Of Energy
Doctor Manhattan came from a world without superpowered beings. He helped the US government and was their main deterrent to Soviet nuclear attack. He could render the warheads inert and even absorb and change the nature of the nuclear energy released.
When he came to the DC Universe, he would eventually face some of the most powerful heroes and completely defeat them. He was able to turn their energies against them completely, even showing the ability to manipulate magical energy. This ability would serve him well against just about any foe.
8 Lucifer Morningstar: Eons Of Conflict
As ruler of Hell, Lucifer had to deal with some of the worst beings in existence. Hell was a constantly squabbling hierarchy of demons trying to gain power and they would often target Lucifer himself in their machinations, which was a huge mistake. Lucifer was much more powerful and canny than them and was always able to defeat any pretenders to his throne.
In his eons of existence, Lucifer has not only dealt with nearly every kind of scheme, but also been a part of many of them. He did it for so long that he got tired of it and decided to leave Hell. His experience in conflict is unprecedented.
7 Doctor Manhattan: A Man Of Learning
Doctor Manhattan's obsession is knowledge. One of the reasons he worked for the US government on his world for so long was because they gave him the means to not only do any experiments he wanted, but to use his powers for all kinds of beneficial scientific endeavors, such as designing an entirely new energy system based on lithium he could synthesize, revolutionizing technology.
All of this learning and knowledge had the added effect of teaching him new ways of using his powers- the more he learned about the universe and the way it worked, the more he could do with his powers.
6 Lucifer Morningstar: Feared By All
Lucifer was once the most powerful, wise, and beautiful angel of them all, and after his fall he still retained all of that. The universe is full of powerful forces, yet they all have one thing in common- they fear Lucifer Morningstar. Gods, angels, demons, it doesn't matter who, they all tread lightly in his presence.
Even beings like the Endless, who gods listen to and fear, are afraid of Lucifer. Morpheus treated him with dignity and respect in an attempt to mollify Lucifer and even the elder Endless, like Destiny and Death, knew better than to trifle with the Star of Morning.
5 Doctor Manhattan: Time's Orphan
Doctor Manhattan doesn't experience time like anyone else. For him, it's all happening at once- the past, present, and future all occurring simultaneously. This gives him a unique, almost unprecedented view of the universe and has allowed him to do some extraordinary things- he knows what's going to happen and yet he also doesn't. It's can be confusing and yet it works for him.
The only thing that can mess with his perception of time are tachyons, which muddle his visions of the future.
4 Lucifer Morningstar: Created A Universe
As powerful as Lucifer is, he can't create things on his own, only transmute them from one thing to another. However, if he works in concert with the archangel Michael or his niece Elaine, he gains creative powers, and he's used this ability once to create an entirely new universe. The whole thing ended badly, but he still was able to do it.
Even though he can't do it on his own, the fact that he was able to create a universe at all is very impressive. He understood how things worked well enough to create one on his own, and that shows just how intelligent he really is.
3 Doctor Manhattan: Hard To Defeat
Doctor Manhattan was created in a terrible accident. He used his prodigious knowledge to reassemble his molecular structure, and this allowed him to learn how to manipulate matter of all kinds and it also made him extremely hard to destroy. There are probably ways to do it, of course, and beings who could, but the problem is figuring out how.
This makes battling Doctor Manhattan a daunting proposition- how does one destroy someone who learned how to reconstruct their molecular structure from scratch the first time they used their powers?
2 Lucifer Morningstar: Actually Immortal
Immortality is a tricky thing. There are many beings who have the potential to live forever and yet can still be killed. Conversely, there are beings who are completely indestructible who will one day die. Lucifer, however, is actually immortal- he will live forever and cannot be killed by anything other than a literal act of God- God himself is the only one who can do away with him.
Fighting Lucifer is a losing proposition, because there's no way to gain a final victory over him. Even on the small chance that someone was able to outmaneuver him, they couldn't kill him and this would give him a chance to come back and destroy them.
1 Winner: Lucifer Morningstar
Doctor Manhattan is one of the most powerful beings in existence, however even his powers are dwarfed by those of Lucifer Morningstar. Lucifer is the second most powerful being in all of creation; he can do just about anything.
As hard as Doctor Manhattan can be to defeat, Lucifer would have the power to do so, whereas nothing Doctor Manhattan can do would put him down.