Akihiko just got the ability 'Mazionga', and to my dismay he doesn't have another ability listed where it normally lists what abilities are yet to come. Is it all over for Akihiko then? I can't imagine wanting to continue using him if he doesn't get some upgrades, but he's one of my favourites and i'd be sad to see him go. And does the same go for other characters? It''ll be a sad day for me when Aigis becomes useless. 
 
Speaking of Aigis, it seems like Shunji's better in seemingly every single way. I've stuck with Aigis because I prefer the character, but am I just deluding myself? Shall I just man up and switch her out with Shinji?

Nope, keep playing the story and something will happen to his persona.

Its a story thing. It will happen to everyone else except the mc.

And switching Aigis out for Shinji is a really bad idea.

" And switching Aigis out for Shinji is a really bad idea. "

Oh thank god, was not looking forward to a teary good bye with Akihiko. And I'm glad I don;t have to use Shinji, I'm not really 'feeling him', whereas Aigis is a badass.

Use Shinji as much as you can, only work on him.