Despite being taller Orga certainly drew the short stick of those two. Mika is just doing excellently the one thing he has always done: fighting. Nothing more, nothing less, plain and simple. But what exactly gives Orga the qualifications to lead this group? Sure, he can make decisions and stick to them without continuously hesitating the second-guessing himself, but that could be viewed as a personality trait, nothing more. However, these guys were the slaves when the old company was still up and running. There's no way Orga actually had any leadership training or education of any sort. He also has very little experience of anything but doing dirty work back on Mars. Mika can fight everywhere the same, but Orga was a fish out of the water the moment they left Mars. I can't help but pity him, but at the same time you have to admit he has actually succeeded splendidly all things considered.
Seeing how this is getting a second season I wonder when Orga dies. Will he die at the very end of this first season, forcing Mika to finally think for himself and do something else in addition to fighting, or will Orga still be in the second season? It's hard to say now, but with the series getting longer, I have a feeling he should die before the end of the second season for it to be more meaningful and for it to launch Mika's personal development. If this had been a single season, he could simply have died heroically in the last ep saving the others, but with plenty of eps left, it could be used for Mika's sake, following the Gurrenn Lagann example.