
Looking up stuff about this online, I found a thread on the skyrim wiki of people discussing this.

I can't seem to find any armor from the vanilla game, or any of my mods, that I think really suits her character. I used to have a mod I made myself that simply switched her default outfit to leather, but after a while I got tired of how generic that looked. Besides, I have a hard time imagining Aela going out into the wilderness hunting animals while dressed in something that besides looking rather heavy would no doubt make quite a lot of noise, which is clearly not ideal for sneaking up on game. Really, the only other armor associated with them is the wolf armor, but again that's the wrong armor type. Besides, Ysgramor wore it, you gain the ability to craft it after going through the companions questline, and its obviously not something nords normally wear anymore, so it still feels like its associated with them. Yeah, ancient nordic armor isn't exactly unique to her, but she is the only female character that wears it by default which at the very least makes her look unique. Another problem is that she's supposed to be a part of the inner circle of the companions, so some generic armor type just feels out of place on her.

Because of that, I always thought her default outfit suited her aesthetically since it looks to be a compromise between being light and heavy. However, she's also a decent front-line warrior who uses a shield.

She's supposed to be a hunter that uses a bow, and such characters normally prefer light armor. Thinking about it, her character is a bit contradictory. Sadly though, I haven't really been able to find a light armor that I think suits her. I know the Unofficial Patch changes her armor skill from light to heavy, but honestly I always thought light armor suited her better due to the fact that she's supposed to an archer who literally has 'the huntress' in her name!
