Red side areas are harder to digest, less pleasing to be in. Steel canyon and atlas park are my favorites - they’re bright, easy on the eyes with clear visuals etc. Redside you start out in gloomy, dirty areas, and it continues that way, with fog and such. Blueside you make excursions into areas with these visuals to fight baddies and then return to the nicer areas.
In addition to the stories, I’d say a big aesthetic drawing me towards redside would be the ATs. Similarly for blueside. When I make a character, I make it a hero AT blueside or villain AT red. And I don’t much like seeing villain ATs blueside. Because of this availability, I also don’t see redside as very attractive. There’s nothing unique to it apart from the stories and those I’ll experience as I suffer from lack of co-players and endure the lack of comfortable home zones.