I would say Hotel Hokke Club Asakusa. They have a buffet style breakfast, and it's open from 6:30 AM so you will have enough time, even you have a plan for the rest of the day. They serve Japanese dishes and European dishes.
Or 銀座ブラジル 浅草支店, they serve the bread. I've heard their sunny side up is so good.
There is a famous bakery called Perican in Asakusa. Many cafes in Tokyo purchase bread from this bakery. They only have takeouts but the flavor is assured. Enjoy fluffy breads from here! Open from 8:00 AM