I think I could bear with you for one day :)
But if you really hate all kinds of graffitti and you're not STRONGLY interested in arts, museums and architecture, it's probably not worth travelling 12h in train for a one-day visit of Basel. To be honest, the best is already in the pictures above, I guess.
And I only like Basel when it's sunny, that's also pretty risky if it's only planned for one fix day!
Well, food, there's a lot of Swiss specialities like "Rösti" and "Basler Läckerli." A football match in the St.Jakob Stadium maybe... :D
But I think I'm totally not interested in the same things like you and I'm not sure if it's gonna be a highlight of your europe trip, then.
You surely had more fun when you'd spend about a week in Switzerland and we visit also different cities like Lucerne, Lugano and Geneva.
So, we'll better do it only if it's a wish of you or you are already bored in Alemania. I keep the invitation open but warn me some days before so I could plan a bit if you'd change your mind.
Otherwise have fun the rest of your trip in Germany and maybe see you on your next europe trip if you survived Kyrgystan :D