"didn't he take down a guy that the mighty avengers together couldn't? True, it was a skrull, but still...."I think he did. But everything from the Marvel Directory to the Marvel Handbook has Mar-Vell as a rather weak character...
Breach, as an alternative variant of Capt Atom (as shown in 52 or one of the spinoffs), should possess vast energy manipulation powers. This seems to be the case from some of the abilities he has used. Not only did he whallop martian Manhunter (as shown above) but he also blasted Superman.
His raw power seems greater than Capt Mar-vell but Mar-vell obviously has far greater experience in the use of his powers.
Breach for the win.