Well, that's a debate among fans for ages! Both Omni-Man from the invincible series and Superman from DC Comics are super powerful characters with their distinct strengths and weaknesses.
Let's first talk about Omni-Man, also known as Nolan Grayson. Omni-Man hails from a planet of Viltrum where everyone is almost god-like. I mean, he can fly, he's got superhuman strength, speed, stamina, and not to forget, his healing powers. And the cherry on top? His aging is slower than humans which pretty much makes him almost invincible.
Now, Superman, the name's already enough, isn't it? Kal-El, the son of Krypton, is someone merely mortals like us have admired since forever. His strengths are quite similar to Omni-Man. He can fly, he's super strong, and fast, he's got his heat vision and freeze breath. Plus, he absorbs sunlight to power himself up.
Admittedly, it’s hard to compare who’s stronger since it comes down to the plot of the stories they belong to. An all-out fistfight without any external favor would indeed be epic. There are instances where Superman held back as he cares for the humans and their world. So, if Superman is not holding back, it's going to be a tough challenge for Omni-Man.
That said, each has their own Achilles' heel. The sun's yellow radiation powers up Superman, but kryptonite is his downfall. Omni-Man, on the other hand, doesn't have any specific weaknesses that we know of apart from the fact he can be weakened by receiving enough physical damage from beings of equal or greater power.
In conclusion, can Omni-Man beat Superman? Honestly speaking, while Omni-Man has more experience due to a longer lifespan, it is still hard to say as Superman also has equally impressive powers and a noble heart. The actual outcome could vary based on countless variables.
So, it's quite difficult to definitively say who would come out on top in a fight. But that's precisely what makes the discussions and debates about them amongst fans so interesting, right?