Before jumping into the details let's talk about both of them.

        Homelander is an Superhero appearing in famous "The Boys" series. Basically, he is knock off of Superman. Homelander's origin is that he was introduced with Compound V at his early stage that gave him super powers. Homelander is really powerful and can take out number of villains and superheros alone. 

      Omni Man is more like superman. He is an alien that came from a planet deep in the space. Omni appeared in the animation series "The Invincible". The origin of Omni man is that he is born at a planet that is run by race of powerful people. He is sent to the planet earth and he starts living here. 

     This is a debate going on among the fans of both heros. There is an animated video based on this topic. In the video, both of the heros fight a deadly battle and try to over power their counter part. It is clearly visible that Omni man is more powerful than homelander as homelander's powers come from a drug on the other hand Omni man was born at a planet with super humans. His power came from birth. It should be noted that Omni man is way more experienced than homelander as Omni man can live up to thousands of years.

Watch the video below to watch the death battle between these two heros and let me know about your opinions in comments.