Everyone has different requirements, some prefer extra performance, I prefer safety, comfort and low noise.
Anyway my A5 came with Hankook Ventus v12 evo2 in 255/35 r19. They have a very good grip (but not the best), excellent mpg and are amazingly quiet on motorways. Mid-range priced.
I do prefer All Seasons tires for extra safety in wet/winter. Michelin Cross Climate+ used to be the best and now they have Cross Climate 2 which is even better.