Aerosmith and for me it's not remotely close. AC/DC are totally an overhyped band esp. by European rock fans. Never got all the fuss and hype for them.
Aerosmith are musically far better and by far more creative band. Their music is not simplistic and generic, it sometimes goes deeper.
And Aerosmith is a way more beloved rock band in the USA than Europe. I think they deserve to be a much more beloved and appreciated band in Europe!